IRF5 regulates airway macrophage metabolic responses.

Interferon regulatory factor 5 (IRF5) is a master regulator of macrophage phenotype and a key transcription factor involved in expression of proinflammatory cytokine responses to microbial and viral infection. Here, we show that IRF5 controls cellular and metabolic responses. By integrating ChIP sequencing (ChIP-Seq) and assay for transposase-accessible chromatin using sequencing (ATAC)-seq data sets, we found that IRF5 directly regulates metabolic genes such as hexokinase-2 (Hk2). The interaction of IRF5 and metabolic genes had a functional consequence, as Irf5-/- airway macrophages but not bone marrow-derived macrophages (BMDMs) were characterized by a quiescent metabolic phenotype at baseline and had reduced ability to utilize oxidative phosphorylation after Toll-like receptor (TLR)-3 activation, in comparison to controls, ex vivo. In a murine model of influenza infection, IRF5 deficiency had no effect on viral load in comparison to wild-type controls but controlled metabolic responses to viral infection, as IRF5 deficiency led to reduced expression of Sirt6 and Hk2. Together, our data indicate that IRF5 is a key component of AM metabolic responses following influenza infection and TLR-3 activation.

A polymorphism that affects OCT-1 binding to the TNF promoter region is associated with severe malaria.

Genetic variation in cytokine promoter regions is postulated to influence susceptibility to infection, but the molecular mechanisms by which such polymorphisms might affect gene regulation are unknown. Through systematic DNA footprinting of the TNF (encoding tumour necrosis factor, TNF) promoter region, we have identified a single nucleotide polymorphism (SNP) that causes the helix-turn-helix transcription factor OCT-1 to bind to a novel region of complex protein-DNA interactions and alters gene expression in human monocytes. The OCT-1-binding genotype, found in approximately 5% of Africans, is associated with fourfold increased susceptibility to cerebral malaria in large case-control studies of West African and East African populations, after correction for other known TNF polymorphisms and linked HLA alleles.

Functional consequences of a polymorphism affecting NF-kappaB p50-p50 binding to the TNF promoter region.

Stimulation of the NF-kappaB pathway often causes p65-p50 and p50-p50 dimers to be simultaneously present in the cell nucleus. A natural polymorphism at nucleotide -863 in the human TNF promoter (encoding tumor necrosis factor [TNF]) region provides an opportunity to dissect the functional interaction of p65-p50 and p50-p50 at a single NF-kappaB binding site. We found that this site normally binds both p65-p50 and p50-p50, but a single base change specifically inhibits p50-p50 binding. Reporter gene analysis in COS-7 cells expressing both p65-p50 and p50-p50 shows that the ability to bind p50-p50 reduces the enhancer effect of this NF-kappaB site. Using an adenoviral reporter assay, we found that the variant which binds p50-p50 results in a reduction of lipopolysaccharide-inducible gene expression in primary human monocytes. This finding adds to a growing body of experimental evidence that p50-p50 can inhibit the transactivating effects of p65-p50 and illustrates the potential for genetic modulation of inflammatory gene regulation in humans by subtle nucleotide changes that alter the relative binding affinities of different forms of the NF-kappaB complex.

A critical role for IRF5 in regulating allergic airway inflammation.

Interferon regulatory factor 5 (IRF5) is a key transcription factor involved in the control of the expression of proinflammatory cytokine and responses to infection, but its role in regulating pulmonary immune responses to allergen is unknown. We used genetic ablation, adenoviral vector-driven overexpression, and adoptive transfer approaches to interrogate the role of IRF5 in pulmonary immunity and during challenge with the aeroallergen, house dust mite. Global IRF5 deficiency resulted in impaired lung function and extracellular matrix (ECM) deposition. IRF5 was also essential for effective responses to inhaled allergen, controlling airway hyperresponsiveness, mucus secretion, and eosinophilic inflammation. Adoptive transfer of IRF5-deficient alveolar macrophages into the wild-type pulmonary milieu was sufficient to drive airway hyperreactivity, at baseline or following antigen challenge. These data identify IRF5-expressing macrophages as a key component of the immune defense of the airways. Manipulation of IRF5 activity in the lung could therefore be a viable strategy for the redirection of pulmonary immune responses and, thus, the treatment of lung disorders.

Conserved kappa B element located downstream of the tumor necrosis factor alpha gene: distinct NF-kappa B binding pattern and enhancer activity in LPS activated murine macrophages.

Transcriptional activation of various genes by lipopolysaccharide (LPS) is known to be mediated, at least in part, by the NF-kappa B/Rel family of transcription factors. We have identified a novel kappa B element located immediately downstream of the TNF-alpha gene that is conserved together with its flanking sequences across species lines and can act as an LPS-responsive enhancer for reporter gene constructs driven by the minimal TNF promoter. In extracts from activated murine macrophages and macrophage cell lines this element binds several non-canonical NF-kappa B/Rel complexes, in addition to p50 (NFKB1) homodimer and p50-p65 (NKFB1-RelA) heterodimer. Combination of high-resolution electrophoretic mobility shift assays (EMSA) with monospecific antibodies and u.v.-cross-linking indicates that the prominent slow migrating complex III contain p65 homodimer and c-Rel. The appearance of complex III in EMSA parallels the translocation of p65 and c-Rel into the nucleus and occurs shortly after LPS induction. Transfection experiments with reporter constructs driven by this kappa B element indicate strong inducibility by LPS and p65, moderate inducibility by c-Rel and repression by p50. Functional activity of sandwich TNF-CAT-TNF constructs further suggests that LPS-inducible transcriptional activation of the TNF gene in murine macrophages may be partly mediated by a downstream enhancer.

Genetic polymorphism of the human tumor necrosis factor region in insulin-dependent diabetes mellitus. Linkage disequilibrium of TNFab microsatellite alleles with HLA haplotypes.

The TNF region within the MHC includes a number of immunologically important genes. Microsatellites TNFa and TNFb adjacent to TNF exhibit extensive polymorphism. Employing a PCR-based technique, we identified TNFab haplotypes and defined their distribution in 97 controls and 48 diabetics of Caucasoid origin in a search for other genes within the MHC potentially associated with IDDM. Twenty-five different TNFab haplotypes were identified. A significant difference (p < 0.0005) in frequency between patients and controls was found for TNFa1b5 (relative risk 53). However, no other TNFab microsatellites demonstrated significantly different frequencies. Among diabetics TNFa1b5 was found to be in linkage disequilibrium with HLA-DR3-B18, a haplotype known to be associated with IDDM. Thus the increased frequency of TNFa1b5 among diabetics could reflect a linkage disequilibrium with a gene within the TNF region or with other genes, including the HLAs, which characterize this haplotype. In both controls and diabetics TNFa2b3 and TNFa7b4 were in linkage disequilibrium with DR3-B8 and DR7, respectively. Among diabetics, TNFa2b1 and TNFa6b5 were in linkage disequilibrium with DR4-B62 and DR4-B44, respectively. It is intriguing that TNFab haplotypes, represented by a short piece of about 200 nucleotides in the untranslated region upstream of TNF beta gene, maintain strong linkage disequilibria with different HLA haplotypes extending over 1 million base pairs. The identification of TNFab microsatellites exhibiting a high polymorphic index in a region lacking known polymorphic markers may provide potentially important information regarding the association of HLA haplotypes with autoimmune diseases, as they are in close proximity to other genes of immunologic importance.

-308 tumor necrosis factor (TNF) polymorphism is not associated with survival in severe sepsis and is unrelated to lipopolysaccharide inducibility of the human TNF promoter.

Tumor necrosis factor (TNF) is recognized as a central mediator of sepsis, septic shock, and multiple organ failure. These host reactions are associated with increased TNF levels in circulation, presumably due to increased TNF production. A previously described nucleotide variation at position -308 in the promoter region of the human TNF gene was shown to be associated with the clinical outcome of malaria. In this study we addressed the relevance of the -308 polymorphism for expression of the human TNF gene in response to bacterial endo- toxin in vivo and in vitro. First, we typed 80 patients suffering from severe sepsis and 153 healthy individuals and found no association of the -308 variation with incidence of the disease. In contrast, the NcoI marker in the closely linked lymphotoxin-alpha (LT-alpha) gene showed association with survivaL This discrepancy can be explained by the linkage of the TNFB2(NcoI) allele to the common TNF1 (-308) allele. Second, we generated reporter gene constructs with the promoter deletions and with both -308 variation in the context of the extended human TNF promoter region. Although such constructs were highly inducible by lipopolysaccharide (LPS) in transient transfections into a macrophage cell line, the -308 variation had no significant effect on transcription, consistent with the promoter deletion study. We conclude that the functional consequence of the -308 polymorphism may be unrelated to transcriptional response of the TNF gene to bacterial endotoxin.

[Nucleotide sequence of two exons of the human T-lymphocyte CD4 receptor gene]. / Nukleotidnaia posledovatel'nost' dvukh ékzonov gena CD4-retseptora T-limfotsitov cheloveka]

Genome DNA encoding the N-part of human CD4 gene located in the 15 kilobase (kb) Sau3a restriction fragment was cloned and nucleotide sequence of a part (3430 b.p.) of this fragment determined. Exons 2 and 3, intron 2, and partially introns 2 and 3 of this gene were located in the sequenced fragment. Six Alu repeats and open reading frames (ORFs) coding for proteins very close to C5 and C3 components of the complement were detected in this fragment.

[Biochemical and immunochemical characteristics of a new oral, chemical cholera bivalent vaccine and results of a trial of the preparation on volunteers]. / Biokhimicheskaia i immunokhimicheskaia kharakteristika novoi oral'noi kholernoi knimicheskoi bivalentnoi vaktsiny i rezul'taty ispytaniia preparata na dobrovol'tsakh.

Oral cholera vaccine contains 45% of O-antigen (serovars Ogawa and Inaba in equal parts) and at least 9 serologically active proteins; of these, toxoid (about 60% of the total amount of protein) and 5 enzymes have been identified: neuraminidase, proteinase, ribonuclease, phospholipase and ATPase. The safety, absence of reactogenicity and definite immunological effectiveness of the preparation in the primary immunization of volunteers have been shown.

KAP1/TRIM28: an inhibitor of IRF5 function in inflammatory macrophages.

IRF5 plays a key role in the induction of pro-inflammatory cytokines, contributing to the plasticity and polarisation of macrophages to an M1 phenotype and initiation of a potent T(H)1-T(H)17 response. To better understand the means of IRF5 transcriptional action, we conducted a screen for IRF5-interacting partners by affinity purification coupled to mass spectrometry and identified KAP1/TRIM28 as a novel protein-protein interaction partner of IRF5. KAP1 acts as a transcriptional co-repressor, chiefly via recruitment of complexes involved in chromatin silencing, such as histone deacetylases and methyltransferases. We mapped the N-terminus of IRF5, encompassing its DNA-binding domain together with a highly intrinsically disordered region, as crucial for the IRF5-KAP1 interaction interface, and demonstrated that IRF5 can also form complexes with the methyltransferase SETDB1. Knockdown of KAP1 (TRIM28) gene expression in human M1 macrophages potentiated IRF5-mediated expression of TNF and other M1 macrophage markers. This effect may be linked to methyltransferase activity of SETDB1, such as trimethylation of lysine 9 of histone 3 (H3K9me3), deposition of which was decreased at the human TNF locus upon KAP1 knockdown. Our study furthers an understanding of the complex molecular interactions between the TRIM and IRF protein families, and highlights a role of the inhibitory properties of KAP1 in association with IRF5-mediated gene expression.

An investigation of transmission ratio distortion in the central region of the human MHC.

Transmission ratio distortion (TRD) describes a significant departure from expected Mendelian inheritance ratios that is fundamental to both the biology of reproduction and statistical genetics. The relatively high fetal wastage in humans, with consequent selection of alleles in utero, makes it likely that TRD is prevalent in the human genome. The central region of the human major histocompatibility complex (MHC) is a strong TRD candidate, as it houses a number of immune and regulatory genes that may be important in pregnancy outcome. We used a nonhaplotype-based method to select 13 tagging SNPs from three central MHC candidate regions, and analysed their transmission in 380 newborns and their parents (1138 individuals). A TRD of 54:46 was noted in favour of the common allele of a promoter SNP in the CLIC1 gene (P = 0.025), with a similar distortion using haplotypes across the same gene region (P = 0.016). We also found evidence that markers in the CLIC1 gene region may have been subject to recent selection (P < 0.001). The study illustrates the potential benefits of screening for TRD and highlights the difficulties encountered therein.

Interaction of AP-1 with a cluster of NF-kappa B binding elements in the human TNF promoter region.

Transcriptional activation of the human TNF gene involves multiple regulatory elements whose functional properties vary between stimuli and cell types. Here we have used a COS-7 expression system to dissect the transactivating potential of NF-kappa B binding sites in the human TNF promoter region from other regulatory influences. In this model, NF-kappa B acts largely through a dense cluster of three binding sites located 600 nt upstream of the transcription start site. We show that the transcriptional activity of this complex is highly sensitive to the p65:p50 ratio that is expressed. We demonstrate that the AP-1 complex c-Jun/Fra2 is capable of binding to this region and that this inhibits the transactivating effects of NF-kappa B. These results are suggestive of a complex regulatory element that mediates fine control rather than acting as a simple on-off switch for TNF gene expression.

Direct evidence for involvement of NF-kappaB in transcriptional activation of tumor necrosis factor by a spirochetal lipoprotein.

Variable major lipoprotein (Vmp) is a major tumor necrosis factor (TNF)-inducing component of Borrelia recurrentis, the agent of louse-borne relapsing fever. B. recurrentis Vmp rapidly stimulates nuclear translocation of NF-kappaB and proinflammatory cytokine gene expression in the human monocyte-like cell line MonoMac 6. By overexpressing disabled mutant IkappaBalpha in MonoMac 6 cells cotransfected with a reporter gene, we provide evidence that NF-kappaB is essential for the transcriptional activation of TNF in this system.

DNA sequence polymorphism at the human tumor necrosis factor (TNF) locus. Numerous TNF/lymphotoxin alleles tagged by two closely linked microsatellites in the upstream region of the lymphotoxin (TNF-beta) gene.

TNF-alpha and lymphotoxin (LT, TNF-beta) genes are tandemly arranged and map within the MHC centromeric to HLA-B and telomeric to the class III genes. Both cytokines encoded by these genes are potent immunomodulators. On the other hand, some MHC-linked autoimmune diseases are characterized by abnormal levels of their expression or inducibility. A search for the putative disease-associated TNF/LT alleles depends on the informative genetic markers at the TNF locus. Previously, a low degree of genetic polymorphism at the human TNF locus has been reported, mostly bi-allelic RFLP. To localize and define additional polymorphic markers, we probed the collection of genomic clones with synthetic tandemly repeated dinucleotides, corresponding to the sequences known as microsatellites. We mapped and characterized three (TC/GA) and one (AC/GT) repeats within cloned 40-kb DNA comprising the human TNF locus. Using a polymerase chain reaction-based technique, we analyzed three of these four microsatellites and observed their length of polymorphism. Using DNA samples from blood donors, two families, and three human cell lines, we detected 13 distinct alleles of the AC/GT microsatellite neighboring human TNF genes. The variability was further increased by simultaneous analysis of the second linked microsatellite. This linked TC/GA repeat showed at least five alleles, whereas the least polymorphic TC/GA repeat located in the first intron of LT (TNF-beta) gene had two alleles. TNF alleles defined by microsatellites were stably inherited and segregated in the Mendelian way. Therefore, we describe thus far the most informative level of DNA sequence polymorphism in this part of human MHC. We propose a nomenclature for microsatellite tagged LT/TNF alleles based on their size and variability, which could also be extended to include RFLP and other not yet identified polymorphic markers. Microsatellite tagged polymorphism described here can be used in systematic linkage studies of HLA-associated diseases.

Oligonucleotide dendrimers: synthesis and use as polylabelled DNA probes.

Oligonucleotide dendrimers were synthesized using a novel phosphoramidite synthon, tris-2,2,2-[3-(4,4'-dimethoxytrityloxy) propyloxymethyl]ethyl- N , N -diisopropylaminocyanethoxy phosphoramidite. Label, incorporated using [gamma-32P]ATP and polynucleotide kinase, was increased in proportion to the number of 5'-ends. There was a similar increase in signal when these multiply labelled oligonucleotides were used as probes to oligonucleotide arrays. A dendrimeric oligonucleotide was used successfully as a primer in the PCR. The strand bearing the dendrimer was resistant to degradation by T7 Gene 6 exonuclease making it easy to convert the double-stranded product of the PCR to a multiply-labelled, single-stranded probe.

1,25-Dihydroxyvitamin D3 induces nitric oxide synthase and suppresses growth of Mycobacterium tuberculosis in a human macrophage-like cell line.

Inducible synthesis of nitric oxide (NO) by macrophages is an important mechanism of the host defense against intracellular infection in mice, but the evidence for significant levels of inducible NO production by human macrophages is controversial. Here we report that the human promyelocytic cell line HL-60, when differentiated to a macrophage-like phenotype, acquires the ability to produce substantial amounts of NO on stimulation with LPS or 1, 25-dihydroxyvitamin D3 (1,25-D3) in the absence of activating factors such as gamma interferon. Expression of the inducible nitric oxide synthase (NOS2) was confirmed by sequencing of the reverse transcription-PCR product from stimulated HL-60 cells. Kinetic studies after lipopolysaccharide stimulation show that NOS2 mRNA levels rise within 3 to 6 h, that conversion of [14C]arginine to [14C]citrulline is maximal at 5 to 6 days, and that levels of reactive nitrogen intermediates stabilize at around 20 microM at 7 to 8 days. We find that 1,25-D3 acts to suppress the growth of Mycobacterium tuberculosis in these cells and that this effect is inhibited by NG-monomethyl-L-arginine, suggesting that vitamin D-induced NO production may play a role in the host defense against human tuberculosis.