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Chromatin remodelling is essential for cardiac development. Interestingly, the role of histone chaperones has not been investigated in this regard. HIRA is a member of the HUCA (HIRA/UBN1/CABIN1/ASF1a) complex that deposits the variant histone H3.3 on chromatin independently of replication. Lack of HIRA has general effects on chromatin and gene expression dynamics in embryonic stem cells and mouse oocytes. Here we describe the conditional ablation of Hira in the cardiogenic mesoderm of mice. We observed surface oedema, ventricular and atrial septal defects and embryonic lethality. We identified dysregulation of a subset of cardiac genes, notably upregulation of troponins Tnni2 and Tnnt3, involved in cardiac contractility and decreased expression of Epha3, a gene necessary for the fusion of the muscular ventricular septum and the atrioventricular cushions. We found that HIRA binds GAGA rich DNA loci in the embryonic heart, and in particular a previously described enhancer of Tnni2/Tnnt3 (TTe) bound by the transcription factor NKX2.5. HIRA-dependent H3.3 enrichment was observed at the TTe in embryonic stem cells (ESC) differentiated toward cardiomyocytes in vitro. Thus, we show here that HIRA has locus-specific effects on gene expression and that histone chaperone activity is vital for normal heart development, impinging on pathways regulated by an established cardiac transcription factor.

Complete STAT1 deficiency is an autosomal recessive primary immunodeficiency caused by null mutations that abolish STAT1-dependent cellular responses to both IFN-[alpha]/[beta] and IFN-[gamma]. Affected children suffer from lethal intracellular bacterial and viral diseases. Here we report a recessive form of partial STAT1 deficiency, characterized by impaired but not abolished IFN-[alpha]/[beta] and IFN-[gamma] signaling. Two affected siblings suffered from severe but curable intracellular bacterial and viral diseases. Both were homozygous for a missense STAT1 mutation: g.C2086T (P696S). This STAT1 allele impaired the splicing of STAT1 mRNA, probably by disrupting an exonic splice enhancer. The misspliced forms were not translated into a mature protein. The allele was hypofunctional, because residual full-length mRNA production resulted in low but detectable levels of normally functional STAT1 proteins. The P696S amino acid substitution was not detrimental. The patients' cells, therefore, displayed impaired but not abolished responses to both IFN-[alpha] and IFN-[gamma]. We also show that recessive STAT1 deficiencies impaired the IL-27 and IFN-[gamma]1 signaling pathways, possibly contributing to the predisposition to bacterial and viral infections, respectively. Partial recessive STAT1 deficiency is what we believe to be a novel primary immunodeficiency, resulting in impairment of the response to at least 4 cytokines (IFN-[alpha]/[beta], IFN-[gamma], IFN-[gamma]1, and IL-27). It should be considered in patients with unexplained, severe, but curable intracellular bacterial and viral infections., Introduction STAT1 is a key signaling component of IFN responses. There are 2 STAT1 mRNAs, STAT1[alpha] and STAT1B, which use distinct polyadenylation sites. STAT1[alpha] is transcribed and spliced from 25 [...]

The transcription factor signal transducer and activator of transcription-1 (STAT1) plays a key role in immunity against mycobacterial and viral infections. Here, we characterize three human STAT1 germline alleles from otherwise healthy patients with mycobacterial disease. The previously reported L706S, like the novel Q463H and E320Q alleles, are intrinsically deleterious for both interferon gamma (IFNG)-induced gamma-activating factor-mediated immunity and interferon alpha (IFNA)-induced interferon-stimulated genes factor 3-mediated immunity, as shown in STAT1-deficient cells transfected with the corresponding alleles. Their phenotypic effects are however mediated by different molecular mechanisms, L706S affecting STAT1 phosphorylation and Q463H and E320Q affecting STAT1 DNA-binding activity. Heterozygous patients display specifically impaired IFNG-induced gamma-activating factor-mediated immunity, resulting in susceptibility to mycobacteria. Indeed, IFNA-induced interferon-stimulated genes factor 3-mediated immunity is not affected, and these patients are not particularly susceptible to viral disease, unlike patients homozygous for other, equally deleterious STAT1 mutations recessive for both phenotypes. The three STAT1 alleles are therefore dominant for IFNG-mediated antimycobacterial immunity but recessive for IFNA-mediated antiviral immunity at the cellular and clinical levels. These STAT1 alleles define two forms of dominant STAT1 deficiency, depending on whether the mutations impair STAT1 phosphorylation or DNA binding.

Chromatin remodelling is essential for cardiac development. Interestingly, the role of histone chaperones has not been investigated in this regard. HIRA is a member of the HUCA (HIRA/UBN1/CABIN1/ASF1a) complex that deposits the variant histone H3.3 on chromatin independently of replication. Lack of HIRA has general effects on chromatin and gene expression dynamics in embryonic stem cells and mouse oocytes. Here we describe the conditional ablation of Hira in the cardiogenic mesoderm of mice. We observed surface oedema, ventricular and atrial septal defects and embryonic lethality. We identified dysregulation of a subset of cardiac genes, notably upregulation of troponins Tnni2 and Tnnt3, involved in cardiac contractility and decreased expression of Epha3, a gene necessary for the fusion of the muscular ventricular septum and the atrioventricular cushions. We found that HIRA binds GAGA rich DNA loci in the embryonic heart, and in particular a previously described enhancer of Tnni2/Tnnt3 (TTe) bound by the transcription factor NKX2.5. HIRA-dependent H3.3 enrichment was observed at the TTe in embryonic stem cells (ESC) differentiated toward cardiomyocytes in vitro. Thus, we show here that HIRA has locus-specific effects on gene expression and that histone chaperone activity is vital for normal heart development, impinging on pathways regulated by an established cardiac transcription factor. [ABSTRACT FROM AUTHOR]

Sustainable water management is a global challenge for the 21st century. One key aspect remains protection against urban flooding. The main objective is to ensure or maintain an adequate level of service for all inhabitants. However, level of service is still difficult to assess and the high-risk locations difficult to identify. In this article, we propose a methodology, which (i) allows water managers to measure the service provided by the urban drainage system with regard to protection against urban flooding; and (ii) helps stakeholders to determine effective strategies for improving the service provided. One key aspect of this work is to use a database of sewer flood event records to assess flood risk. Our methodology helps urban water managers to assess the risk of sewer flooding; this approach does not seek to predict flooding but rather to inform decision makers on the current level of risk and on actions which need to be taken to reduce the risk. This work is based on a comprehensive definition of risk, including territorial vulnerability and perceptions of urban water stakeholders. This paper presents the results and the methodological contributions from implementing the methodology on two case studies: the cities of Lyon and Mulhouse. [ABSTRACT FROM AUTHOR]

Germline mutations in CYBB, the human gene encoding the gp91phox subunit of the phagocyte NADPH oxidase, impair the respiratory burst of all types of phagocytes and result in X-linked chronic granulomatous disease (CGD). We report here two kindreds in which otherwise healthy male adults developed X-linked recessive Mendelian susceptibility to mycobacterial disease (MSMD) syndromes. These patients had previously unknown mutations in CYBB that resulted in an impaired respiratory burst in monocyte-derived macrophages but not in monocytes or granulocytes. The macrophage-specific functional consequences of the germline mutation resulted from cell-specific impairment in the assembly of the NADPH oxidase. This 'experiment of nature' indicates that CYBB is associated with MSMD and demonstrates that the respiratory burst in human macrophages is a crucial mechanism for protective immunity to tuberculous mycobacteria. [ABSTRACT FROM AUTHOR]

Interferon (IFN) was originally identified as a substance ‘interfering’ with viral replication in vitro. The first IFNs to be identified were classified as type I IFNs (IFN-α/β and related molecules), two other types have since been identified: type II IFN (IFN-γ) and type III IFNs (IFN-λ). Each IFN binds to one of three type-specific receptors. In the mouse model of experimental infections in vivo, IFN-α/β are essential for immunity to most viruses tested, whereas IFN-γ is important for immunity to a smaller number of viruses, together with bacteria, fungi, and parasites, consistent with IFN-γ acting as the ‘macrophage activating factor.’ The precise role of IFN-λ remains unclear. In recent years, inborn errors affecting the production of, or the response to, IFNs have been reported in human patients, shedding light onto the function of IFNs in natura. Disorders of IFN-γ production, caused by IL12B, IL12RB1, and specific NEMO mutations, or of IFN-γ responses, caused by IFNGR1, IFNGR2, and dominant STAT1 mutations, confer predisposition to mycobacterial disease in patients resistant to most viruses. By contrast, disorders of IFN-α/β and IFN-λ production, caused by UNC93B1 and TLR3 mutations, confer predisposition to herpes simplex encephalitis (HSE) in otherwise healthy patients. Consistently, patients with impaired responses to IFN-α/β, IFN-γ, and presumably IFN-λ (carrying recessive mutations in STAT1), or with impaired responses to IFN-α/β and impaired IFN-γ production (carrying mutations in TYK2), or with impaired production of IFN-α/β, IFN-γ, and IFN-λ (carrying specific mutations in NEMO), are vulnerable to mycobacterial and viral infections, including HSE. These experiments of nature suggest that the three types of IFNs play at least two different roles in host defense. IFN-γ is essential for anti-mycobacterial immunity, whereas IFN-α/β and IFN-λ are essential for anti-viral immunity. Future studies in humans aim to define the specific roles of IFN-α/β and IFN-λ types and individual molecules in host defense in natura. [ABSTRACT FROM AUTHOR]

The transcription factor signal transducer and activator of transcription-1 (STAT1) plays a key role in immunity against mycobacterial and viral infections. Here, we characterize three human STAT1 germline alleles from otherwise healthy patients with mycobacterial disease. The previously reported L706S, like the novel Q463H and E320Q alleles, are intrinsically deleterious for both interferon gamma (IFNG)-induced gamma-activating factor-mediated immunity and interferon alpha (IFNA)-induced interferon-stimulated genes factor 3-mediated immunity, as shown in STAT1-deficient cells transfected with the corresponding alleles. Their phenotypic effects are however mediated by different molecular mechanisms, L706S affecting STAT1 phosphorylation and Q463H and E320Q affecting STAT1 DNA-binding activity. Heterozygous patients display specifically impaired IFNG-induced gamma-activating factor-mediated immunity, resulting in susceptibility to mycobacteria. Indeed, IFNA-induced interferon-stimulated genes factor 3-mediated immunity is not affected, and these patients are not particularly susceptible to viral disease, unlike patients homozygous for other, equally deleterious STAT1 mutations recessive for both phenotypes. The three STAT1 alleles are therefore dominant for IFNG-mediated antimycobacterial immunity but recessive for IFNA-mediated antiviral immunity at the cellular and clinical levels. These STAT1 alleles define two forms of dominant STAT1 deficiency, depending on whether the mutations impair STAT1 phosphorylation or DNA binding. [ABSTRACT FROM AUTHOR]

Germline mutations in five autosomal genes involved in interleukin (IL)-12-dependent, interferon (IFN)-γ-mediated immunity cause Mendelian susceptibility to mycobacterial diseases (MSMD). The molecular basis of X-linked recessive (XR)-MSMD remains unknown. We report here mutations in the leu cine zipper (LZ) domain of the NF-κB essential modulator (NEMO) gene in three unrelated kindreds with XR-MSMD. The mutant proteins were produced in normal amounts in blood and fibroblastic cells. However, the patients' monocytes presented an intrinsic defect in T cell-dependent IL-12 production, resulting in defective IFN-γ, secretion by T cells. IL-12 production was also impaired as the result of a specific defect in NEMO- and NF-κB/c-Rel-mediated CD40 signaling after the stimulation of monocytes and dendritic cells by CD40L-expressing T cells and fibroblasts, respectively. However, the CD40-dependent up-regulation of costimulatory molecules of dendritic cells and the proliferation and immunoglobulin class switch of B cells were normal. Moreover, the patients' blood and fibroblastic cells responded to other NF-KB activators, such as tumor necrosis factor-α, IL-1β, and lipopolysaccharide. These two mutations in the NEMO 17 domain provide the first genetic etiology of XR-MSMD. They also demonstrate the importance of the T cell- and CD40L-triggered, CD40-, and NEMO/NF-κB/c-Rel-mediated induction of IL-12 by monocyte-derived cells for protective immunity to mycobacteria in humans. [ABSTRACT FROM AUTHOR]

We describe the case of a 2-year-old boy with disseminated infection by a rapidly growing, poorly pathogenic mycobacterial species that belonged to the Mycobacterium fortuitum-Mycobacterium peregrinum complex. He had a severe course characterized by a poor response to treatment and recurrent lymph node abscess formation. Sequencing of the interferon-gamma receptor 1 gene (IFNgammaR1) revealed that he was homozygous for a novel null mutation, 453delT. Patients presenting with disseminated infections by rapidly growing environmental mycobacteria must be investigated for complete IFNgammaR1 deficiency. The spectrum of IFNgammaR1 genotypes associated with this immunological disorder is expanding. [ABSTRACT FROM AUTHOR]

Disseminated BCG infection is a rare complication of vaccination that occurs in patients with impaired immunity. In recent years, a series of inherited disorders of the IL-12-IFN-gamma axis have been described that predispose affected individuals to disseminated disease caused by BCG, environmental Mycobacteria, and non-typhoidal Salmonella. The routine immunological work-up of these patients is normal and the diagnosis requires specific investigation of the IL-12-IFN-gamma circuit. We report here the first two such patients originating from and living in Iran. The first child is two years old and suffers from complete IFN-gamma receptor 2 deficiency and disseminated BCG infection. He is currently in clinical remission thanks to prolonged multiple antibiotic therapy. The other, a 28-year-old adult, suffers from IL-12p40 deficiency and presented with disseminated BCG infection followed by recurrent episodes of systemic salmonellosis. He is now doing well. A third patient of Iranian descent, living in North America, was reported elsewhere to suffer from IL-12Rbeta1 deficiency. These three patients thus indicate that various inherited defects of the IL-12-IFN-gamma circuit can be found in Iranian people. In conclusion we recommend to consider the disorders of the IL-12-IFN-gamma circuit in all patients with severe BCG infection, disseminated environmental mycobacterial disease, or systemic non-typhoidal salmonellosis, regardless of their ethnic origin and country of residence. [ABSTRACT FROM AUTHOR]

Mutations involving gains of glycosylation have been considered rare, and the pathogenic role of the new carbohydrate chains has never been formally established. We identified three children with mendelian susceptibility to mycobacterial disease who were homozygous with respect to a missense mutation in IFNGR2 creating a new N-glycosylation site in the IFNγR2 chain. The resulting additional carbohydrate moiety was both necessary and sufficient to abolish the cellular response to IFNγ. We then searched the Human Gene Mutation Database for potential gain-of-N-glycosylation missense mutations; of 10,047 mutations in 577 genes encoding proteins trafficked through the secretory pathway, we identified 142 candidate mutations (∼1.4%) in 77 genes (∼13.3%). Six mutant proteins bore new N-linked carbohydrate moieties. Thus, an unexpectedly high proportion of mutations that cause human genetic disease might lead to the creation of new N-glycosylation sites. Their pathogenic effects may be a direct consequence of the addition of N-linked carbohydrate. [ABSTRACT FROM AUTHOR]

The IL-12/IFN-γ axis is crucial for protective immunity to Mycobacterium in humans and mice. Our goal was to analyze the relative contribution of various human blood cell subsets and molecules to the production of, or response to IL-12 and IFN-γ. We designed an assay for the stimulation of whole blood by live M. bovis Bacillus Calmette-Guérin (BCG) alone, or BCG plus IL-12 or IFN-γ, measuring IFN-γ and IL-12 levels. We studied patients with a variety of specific inherited immunodeficiencies resulting in a lack of leukocytes, or T, B, and/or NK lymphocytes, or polymorphonuclear cells, or a lack of expression of key molecules such as HLA class II, CD40L, NF-κB essential modulator (NEMO), and IL-1 receptor-associated kinase-4 (IRAK-4). Patients with deficiencies in IL-12p40, IL-12 receptor β1 chain (IL-12Rβ1), IFN-γR1, IFN-γR2, and STAT-1 were used as internal controls. We showed that monocytes were probably the main producers of IL-12, and that NK and T cells produced similar amounts of IFN-γ. NEMO and IRAK-4 were found to be important for IL-12 production and subsequent IFN-γ production, while a lack of CD40L or HLA class II had no major impact on the IL-12/IFN-γ axis. The stimulation of whole blood by live BCG thus triggers the IL-12/IFN-γ axis by an IRAK-4- and NEMO-dependent, non-cognate interaction between monocytes, NK, and T lymphocytes. [ABSTRACT FROM AUTHOR]

The receptors for interferon-α/β (IFN-α/β) and IFN-γ activate components of the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, leading to the formation of at least two transcription factor complexes. STAT1 interacts with STAT2 and p48/IRF-9 to form the transcription factor IFN-stimulated gene factor 3 (ISGF3). STAT1 dimers form γ-activated factor (GAF). ISGF3 is induced mainly by IFN-α/β, and GAF by IFN-γ, although both factors can be activated by both types of IFN. Individuals with mutations in either chain of the IFN-γ receptor (IFN-γR) are susceptible to infection with mycobacteria. A heterozygous STAT1 mutation that impairs GAF but not ISGF3 activation has been found in other individuals with mycobacterial disease. No individuals with deleterious mutations in the IFN-α/β signaling pathway have been described. We report here two unrelated infants homozygous with respect to mutated STAT1 alleles. Neither IFN-α/β nor IFN-γ activated STATl-containing transcription factors. Like individuals with IFN-γR deficiency, both infants suffered from mycobacterial disease, but unlike individuals with IFN-γR deficiency, both died of viral disease. Viral multiplication was not inhibited by recombinant IFN-α/β in cell lines from the two individuals. Inherited impairment of the STAT1-dependent response to human IFN-α/β thus results in susceptibility to viral disease. [ABSTRACT FROM AUTHOR]

Abstract: Nontuberculous mycobacterial infections are rare in immunocompetent children, and usually present as adenitis. We report a case of a 6-year-old girl with a multifocal chronic osteomyelitis and pulmonary localisation due to Mycobacterium intracellulare associated with an autosomal dominant mutation of interferon gamma receptor 1 gene (INFGR1) leading to a syndrome of mendelian predisposition to mycobacteria infections by partial deficiency of intracellular signalisation of gamma interferon. This child has been cured with anti-mycobacteria drugs and gamma interferon. This report focus on the importance of looking for a susceptibility of the host to infectious diseases, which can lead to a specific treatment. As far as we know, this is the first case described in a tropical area. [Copyright &y& Elsevier]

Summary: Disseminated disease caused by non-tuberculous, environmental mycobacteria (EM) reflects impaired host immunity. Disseminated disease caused by Mycobacterium scrofulaceum has primarily been reported in patients with AIDS. Moreover, observing M. scrofulaceum as the agent of localized disease in childhood has become increasingly rare. We report the first case of disseminated disease caused by M. scrofulaceum in a child with inherited interferon-γ receptor 1 (IFN-γR1) complete deficiency. As in this case, mycobacterial bone infections in IFN-γR1 deficiency can sometimes mimic the clinical picture of chronic recurrent multifocal osteomyelitis. [Copyright &y& Elsevier]

Abstract: Type I interferons (IFN-α/β and related molecules) are essential for protective immunity to experimental infection by numerous viruses in the mouse model. In recent years, human primary immunodeficiencies affecting either the production of (UNC-93B deficiency) or the response to (STAT1 and TYK2 deficiencies) these IFNs have been reported. Affected patients are highly susceptible to certain viruses. Patients with STAT1 or TYK2 deficiency are susceptible to multiple viruses, including herpes simplex virus-1 (HSV-1), whereas UNC-93B-deficient patients present isolated HSV-1 encephalitis. However, these immunological defects are not limited to type I IFN-mediated immunity. Impaired type II IFN (IFN-γ)-mediated immunity plays no more than a minor role in the pathogenesis of viral diseases in these patients, but the contribution of impaired type III IFN (IFN-λ)-mediated immunity remains to be determined. These novel inherited disorders strongly suggest that type I IFN-mediated immunity is essential for protection against natural infections caused by several viruses in humans. [Copyright &y& Elsevier]

Abstract: Mendelian susceptibility to mycobacterial diseases confers predisposition to clinical disease caused by weakly virulent mycobacterial species in otherwise healthy individuals. Since 1996, disease-causing mutations have been found in five autosomal genes (IFNGR1, IFNGR2, STAT1, IL12B, IL12BR1) and one X-linked gene (NEMO). These genes display a high degree of allelic heterogeneity, defining at least 13 disorders. Although genetically different, these conditions are immunologically related, as all result in impaired IL-12/23-IFN-γ-mediated immunity. These disorders were initially thought to be rare, but have now been diagnosed in over 220 patients from over 43 countries worldwide. We review here the molecular, cellular, and clinical features of patients with inborn errors of the IL-12/23-IFN-γ circuit. [Copyright &y& Elsevier]

Summary: Polycomb repressive complex 2 (PRC2) regulates gene expression during lineage specification through trimethylation of lysine 27 on histone H3 (H3K27me3). In Drosophila, polycomb binding sites are dynamic chromatin regions enriched with the histone variant H3.3. Here, we show that, in mouse embryonic stem cells (ESCs), H3.3 is required for proper establishment of H3K27me3 at the promoters of developmentally regulated genes. Upon H3.3 depletion, these promoters show reduced nucleosome turnover measured by deposition of de novo synthesized histones and reduced PRC2 occupancy. Further, we show H3.3-dependent interaction of PRC2 with the histone chaperone, Hira, and that Hira localization to chromatin requires H3.3. Our data demonstrate the importance of H3.3 in maintaining a chromatin landscape in ESCs that is important for proper gene regulation during differentiation. Moreover, our findings support the emerging notion that H3.3 has multiple functions in distinct genomic locations that are not always correlated with an “active” chromatin state. [ABSTRACT FROM AUTHOR]

Some Toll and Toll-like receptors (TLRs) provide immunity to experimental infections in animal models, but their contribution to host defense in natural ecosystems is unknown. We report a dominant-negative TLR3 allele in otherwise healthy children with herpes simplex virus 1 (HSV-1) encephalitis. TLR3 is expressed in the central nervous system (CNS), where it is required to control HSV-1, which spreads from the epithelium to the CNS via cranial nerves. TLR3 is also expressed in epithelial and dendritic cells, which apparently use TLR3-independent pathways to prevent further dissemination of HSV-1 and to provide resistance to other pathogens in TLR3-deficient patients. Human TLR3 appears to be redundant in host defense to most microbes but is vital for natural immunity to HSV-1 in the CNS, which suggests that neurotropic viruses have contributed to the evolutionary maintenance of TLR3. [ABSTRACT FROM AUTHOR]