Interferon-gamma improves splicing efficiency of CYBB gene transcripts in an interferon-responsive variant of chronic granulomatous disease due to a splice site consensus region mutation

Gene regulation in inborn errors of immunity: Implications for gene therapy design and efficacy

Inborn errors of immunity (IEI) present a unique paradigm in the realm of gene therapy, emphasizing the need for precision in therapeutic design. As gene therapy transitions from broad-spectrum gene addition to careful modification of specific genes, the enduring safety and effectiveness of these therapies in clinical settings have become crucial. This review discusses the significance of IEIs as foundational models for pioneering and refining precision medicine. We explore the capabilities of gene addition and gene correction platforms in modifying the DNA sequence of primary cells tailored for IEIs. The review uses four specific IEIs to highlight key issues in gene therapy strategies: X-linked agammaglobulinemia (XLA), X-linked chronic granulomatous disease (X-CGD), X-linked hyper IgM syndrome (XHIGM), and immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX). We detail the regulatory intricacies and therapeutic innovations for each disorder, incorporating insights from relevant clinical trials. For most IEIs, regulated expression is a vital aspect of the underlying biology, and we discuss the importance of endogenous regulation in developing gene therapy strategies.

Improving Access to Therapy for Patients With Inborn Errors of Immunity: A Call to Action

Breakthroughs in sequencing technology, targeted immunotherapy, and immune reconstituting treatment have increased the pool of patients with inborn errors of immunity, requiring expertise from clinical immunologists. A growing category of immunodeficiency, presenting as primary immune regulatory disorder and secondary immunodeficiency due to targeted immune therapy for cancer and autoimmunity, has added to the growing burden of patients needing access to immune-supportive therapy. The confluence of a growing population of patients needing a clinical immunologist, complex payer structures, and inadequate health care representation will exacerbate current problems with access to therapy. Patients, health care providers, researchers, public and private payers, and industry must come together to find solutions to improve access to therapy. In this article, we reviewed the major topics regarding access to therapy for patients with immunodeficiency.

Efficacy and Safety of Interferon-Gamma in Chronic Granulomatous Disease: a Systematic Review and Meta-analysis

BACKGROUND

Chronic granulomatous disease (CGD) is a primary immunodeficiency with increased susceptibility to several bacteria, fungi, and mycobacteria, caused by defective or null superoxide production by the NADPH oxidase enzymatic complex. Accepted treatment consists mainly of antimicrobial prophylaxis. The role of human recombinant subcutaneous interferon-gamma (IFNγ) is less clear since the available evidence on its efficacy derives mainly from a single clinical trial that has been challenged.

OBJECTIVE

We aimed to assess the efficacy and safety of IFNγ as an added treatment for CGD when compared to antimicrobial prophylaxis alone.

METHODS

A literature search was conducted using MeSH terms "Chronic granulomatous disease" AND ("interferon gamma" OR "interferon-gamma"), as well as antibiotics, placebo, no therapy, clinical trial, and trial, on MEDLINE, EMBASE, LILACS, WHOs, CENTRAL, KOREAMED, The Cochrane Library, clinicaltrials.gov, and abstracts from meetings, from 1976 to July 2022. We included clinical trials (CT) and prospective follow-up studies and registered the number of serious infections (requiring hospitalization and IV antibiotics) and deaths, adverse events, and autoimmune complications, in patients treated for CGD with antimicrobial prophylaxis plus IFN-γ, versus antimicrobial prophylaxis alone. We assessed the quality of the studies using risk of bias and STROBE. We performed a meta-analysis by calculating both Peto's odds ratio (OR) and risk reduction (RR) through the Mantel-Haenszel method with a fixed-effect model, using Review Manager 5.4, and we reported the number needed to treat (NNT).

RESULTS

We identified 54 matches from databases and 4 from other sources. We excluded 12 duplicates, 7 titles, and 9 abstracts for relevance, after which we had 30 eligible studies. Twenty-four were then excluded after reading the full text. Six papers were included: one randomized CT and 5 follow-up studies. In total, 324 patients with Chronic granulomatous disease were followed for 319 months under treatment with antibiotic prophylaxis plus interferon-gamma or placebo (or antibiotic prophylaxis alone), reported between the years 1991 and 2016. Three of the studies included a control group, allowing for the aggregate analysis of efficacy (prevention of serious infections). The aggregate OR was 0.49, with a 95% confidence interval of 0.19 to 1.23. The risk ratio for serious infection was 0.56 (95%CI 0.35-0.90) under IFN-γ. The meta-analysis thus favors interferon-gamma for a risk reduction of serious infection.

DISCUSSION

The results from this meta-analysis support the use of IFN-γ in the treatment of patients with CGD. However, we found insufficient clinical evidence and believe more clinical trials are needed to better assess the efficacy and long-term safety of IFN-γ.

Tissue-specific abundance of interferon-gamma drives regulatory T cells to restrain DC1-mediated priming of cytotoxic T cells against lung cancer

Local environmental factors influence CD8+ T cell priming in lymph nodes (LNs). Here, we sought to understand how factors unique to the tumor-draining mediastinal LN (mLN) impact CD8+ T cell responses toward lung cancer. Type 1 conventional dendritic cells (DC1s) showed a mLN-specific failure to induce robust cytotoxic T cells responses. Using regulatory T (Treg) cell depletion strategies, we found that Treg cells suppressed DC1s in a spatially coordinated manner within tissue-specific microniches within the mLN. Treg cell suppression required MHC II-dependent contact between DC1s and Treg cells. Elevated levels of IFN-γ drove differentiation Treg cells into Th1-like effector Treg cells in the mLN. In patients with cancer, Treg cell Th1 polarization, but not CD8+/Treg cell ratios, correlated with poor responses to checkpoint blockade immunotherapy. Thus, IFN-γ in the mLN skews Treg cells to be Th1-like effector Treg cells, driving their close interaction with DC1s and subsequent suppression of cytotoxic T cell responses.

Precision medicine: The use of tailored therapy in primary immunodeficiencies

Primary immunodeficiencies (PID) are rare, complex diseases that can be characterised by a spectrum of phenotypes, from increased susceptibility to infections to autoimmunity, allergy, auto-inflammatory diseases and predisposition to malignancy. With the introduction of genetic testing in these patients and wider use of next-Generation sequencing techniques, a higher number of pathogenic genetic variants and conditions have been identified, allowing the development of new, targeted treatments in PID. The concept of precision medicine, that aims to tailor the medical interventions to each patient, allows to perform more precise diagnosis and more importantly the use of treatments directed to a specific defect, with the objective to cure or achieve long-term remission, minimising the number and type of side effects. This approach takes particular importance in PID, considering the nature of causative defects, disease severity, short- and long-term complications of disease but also of the available treatments, with impact in life-expectancy and quality of life. In this review we revisit how this approach can or is already being implemented in PID and provide a summary of the most relevant treatments applied to specific diseases.

Geographic Variability and Pathogen-Specific Considerations in the Diagnosis and Management of Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a rare but serious primary immunodeficiency with varying prevalence and rates of X-linked and autosomal recessive disease worldwide. Functional defects in the phagocyte nicotinamide adenine dinucleotide phosphate oxidase complex predispose patients to a relatively narrow spectrum of bacterial and fungal infections that are sometimes fastidious and often difficult to identify. When evaluating and treating patients with CGD, it is important to consider their native country of birth, climate, and living situation, which may predispose them to types of infections that are atypical to your routine practice. In addition to recurrent and often severe infections, patients with CGD and X-linked female carriers are also susceptible to developing many non-infectious complications including tissue granuloma formation and autoimmunity. The DHR-123 oxidation assay is the gold standard for making the diagnosis and it along with genetic testing can help predict the severity and prognosis in patients with CGD. Disease management focuses on prophylaxis with antibacterial, antifungal, and immunomodulatory medications, prompt identification and treatment of acute infections, and prevention of secondary granulomatous complications. While hematopoietic stem-cell transplantation is the only widely available curative treatment for patients with CGD, recent advances in gene therapy may provide a safer, more direct alternative.

The extended understanding of chronic granulomatous disease

PURPOSE OF REVIEW

We briefly address the advances in genetics, pathophysiology, and phenotypes of chronic granulomatous disease (CGD). This is one of the most studied primary immunodeficiencies, which comprise mutations in genes encoding the different subunits of the NADPH oxidase system. Those mutations lead to defective reactive oxygen species production, and consequently a failure to eliminate pathogens.

RECENT FINDINGS

Patients with CGD are susceptible to fungal, bacterial, and parasitic infections. Other symptoms, as systemic adverse effects to BCG vaccine and hyperinflammation, are also important clinical conditions in this disease. This wide-ranging clinical spectrum of CGD comes from heterogeneity of mutations, X-linked-CGD or autosomal recessive inheritance, and diverse environmental pressure factors. Early accurate diagnosis and prompt treatment are necessary to diminish the consequences of the disease. The most used diagnostic tests are dihydrorhodamine, cytochrome c reduction, and luminol-enhanced chemiluminescence assay.

SUMMARY

The determination of mutations is essential for diagnosis confirmation and genetic counseling. CGD treatment usually includes prophylactic antibiotics and antifungals. Prophylactic recombinant human interferon-γ, immunosuppressors or immune modulators may be, respectively, indicated for preventing infections or inflammatory manifestations. Hematopoietic stem cell transplantation and gene therapy are currently the available options for curative treatment of CGD.

Gene expression in chronic granulomatous disease and interferon-γ receptor-deficient cells treated in vitro with interferon-γ

Interferon-γ (IFN-γ) plays an important role in innate and adaptive immunity against intracellular infections and is used clinically for the prevention and control of infections in chronic granulomatous disease (CGD) and inborn defects in the IFN-γ/interleukin (IL)-12 axis. Using transcriptome profiling (RNA-seq), we sought to identify differentially expressed genes, transcripts and exons in Epstein-Barr virus-transformed B lymphocytes (B-EBV) cells from CGD patients, IFN-γ receptor deficiency patients, and normal controls, treated in vitro with IFN-γ for 48 hours. Our results show that IFN-γ increased the expression of a diverse array of genes related to different cellular programs. In cells from normal controls and CGD patients, IFN-γ-induced expression of genes relevant to oxidative killing, nitric oxide synthase pathway, proteasome-mediated degradation, antigen presentation, chemoattraction, and cell adhesion. IFN-γ also upregulated genes involved in diverse stages of messenger RNA (mRNA) processing including pre-mRNA splicing, as well as others implicated in the folding, transport, and assembly of proteins. In particular, differential exon expression of WARS (encoding tryptophanyl-transfer RNA synthetase, which has an essential function in protein synthesis) induced by IFN-γ in normal and CGD cells suggests that this gene may have an important contribution to the benefits of IFN-γ treatment for CGD. Upregulation of mRNA and protein processing related genes in CGD and IFNRD cells could mediate some of the effects of IFN-γ treatment. These data support the concept that IFN-γ treatment may contribute to increased immune responses against pathogens through regulation of genes important for mRNA and protein processing.

Alternative Splicing of NOX4 in the Failing Human Heart

Increased oxidative stress is a major contributor to the development and progression of heart failure, however, our knowledge on the role of the distinct NADPH oxidase (NOX) isoenzymes, especially on NOX4 is controversial. Therefore, we aimed to characterize NOX4 expression in human samples from healthy and failing hearts. Explanted human heart samples (left and right ventricular, and septal regions) were obtained from patients suffering from heart failure of ischemic or dilated origin. Control samples were obtained from donor hearts that were not used for transplantation. Deep RNA sequencing of the cardiac transcriptome indicated extensive alternative splicing of the NOX4 gene in heart failure as compared to samples from healthy donor hearts. Long distance PCR analysis with a universal 5′-3′ end primer pair, allowing amplification of different splice variants, confirmed the presence of the splice variants. To assess translation of the alternatively spliced transcripts we determined protein expression of NOX4 by using a specific antibody recognizing a conserved region in all variants. Western blot analysis showed up-regulation of the full-length NOX4 in ischemic cardiomyopathy samples and confirmed presence of shorter isoforms both in control and failing samples with disease-associated expression pattern. We describe here for the first time that NOX4 undergoes extensive alternative splicing in human hearts which gives rise to the expression of different enzyme isoforms. The full length NOX4 is significantly upregulated in ischemic cardiomyopathy suggesting a role for NOX4 in ROS production during heart failure.

[Primary immunodeficiencies in seriously ill children: Report of 3 clinical cases]

Primary immunodeficiency diseases (PID) are congenital disorders secondary to an impaired immune response. Infections, autoimmune disorders, atopy, and lymphoproliferative syndromes are commonly associated with this disorder.

OBJECTIVE

To present and discuss 3 infants diagnosed with PID.

CLINICAL CASES

The cases are presented of three patients with PID diagnosed during their first admission to a Paediatric Intensive Critical Care Unit. The first patient, a 4-month-old infant affected by a severe pneumonia, and was diagnosed as a Severe Combined Immunodeficiency Disease. The second patient was an 8-month-old infant with Candida lusitaniae mesenteric adenitis, and diagnosed with a Chronic Granulomatous Disease. The last patient, a 6-month-old infant presented with ecthyma gangrenosum and X-linked agammaglobulinaemia.

CONCLUSION

PID should be suspected when an infectious disease does not responde to the appropriate therapy within the expected period. An update of each disease is presented.

Modern management of phagocyte defects

Phagocytic neutrophil granulocytes are among the first immune cells active at sites of infection, forming an important first-line defense against invading microorganisms. Congenital immune defects concerning these phagocytes may be due to reduced neutrophil numbers or function. Management of affected patients depends on the type and severity of disease. Here, we provide an overview of causes and treatment of diseases associated with congenital neutropenia, as well as defects of the phagocytic respiratory burst.

Aspergillosis in Chronic Granulomatous Disease

Patients with chronic granulomatous disease (CGD) have the highest life-time incidence of invasive aspergillosis and despite the availability of antifungal prophylaxis, infections by Aspergillus species remain the single most common infectious cause of death in CGD. Recent developments in curative treatment options, such as haematopoietic stem cell transplantation, will change the prevalence of infectious complications including invasive aspergillosis in CGD patients. However, invasive aspergillosis in a previously healthy host is often the first presenting feature of this primary immunodeficiency. Recognizing the characteristic clinical presentation and understanding how to diagnose and treat invasive aspergillosis in CGD is of utmost relevance to improve clinical outcomes. Significant differences exist in fungal epidemiology, clinical signs and symptoms, and the usefulness of non-culture based diagnostic tools between the CGD host and neutropenic patients, reflecting underlying differences in the pathogenesis of invasive aspergillosis shaped by the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase deficiency.

Orofacial adverse effects of biological agents

Biological agents (BA) are increasingly used effectively in the treatment of a range of disorders, but to date, their application in diseases affecting the orofacial region has been fairly limited. Several orofacial adverse effects related to BA have been recently reported. However, the evidence for such adverse reactions is not always strong, and some of the adverse effects of BA have only been reported in case reports or case series. Most reactions to BA reported thus far have been in association with antitumor necrosis factor-α agents, which is not surprising, as these are the most widely-used BA. In the present study, the orofacial adverse effects are reported with various BA in order to sensitize clinicians to the possibilities. In addition, we briefly summarize the mode of action and indications of these BA. As the use and range of BA increases, the number and diversity of adverse effects might well increase. Despite the adverse effects of biological agents, these may often be less serious than the adverse effects of the more traditional immunosuppressive agents.

ICON: the early diagnosis of congenital immunodeficiencies

Primary immunodeficiencies are intrinsic defects in the immune system that result in a predisposition to infection and are frequently accompanied by a propensity to autoimmunity and/or immunedysregulation. Primary immunodeficiencies can be divided into innate immunodeficiencies, phagocytic deficiencies, complement deficiencies, disorders of T cells and B cells (combined immunodeficiencies), antibody deficiencies and immunodeficiencies associated with syndromes. Diseases of immune dysregulation and autoinflammatory disorder are many times also included although the immunodeficiency in these disorders are often secondary to the autoimmunity or immune dysregulation and/or secondary immunosuppression used to control these disorders. Congenital primary immunodeficiencies typically manifest early in life although delayed onset are increasingly recognized. The early diagnosis of congenital immunodeficiencies is essential for optimal management and improved outcomes. In this International Consensus (ICON) document, we provide the salient features of the most common congenital immunodeficiencies.

Pediatric allergy and immunology in Brazil

The subspecialty of pediatric allergy and immunology in Brazil is in its early years and progressing steadily. This review highlights the research developed in the past years aiming to show the characteristics of allergic and immunologic diseases in this vast country. Epidemiologic studies demonstrated the high prevalence of asthma in infants, children, and adolescents. Mortality rates and average annual variation of asthma hospitalization have reduced in all pediatric age groups. Indoor aeroallergen exposure is excessively high and contributes to the high rates of allergy sensitization. Prevalence of food allergy has increased to epidemic levels. Foods (35%), insect stings (30%), and drugs (23%) are the main etiological agents of anaphylaxis in children and adolescents. Molecular diagnosis of primary immunodeficiencies (PID) showed a high incidence of fungal infections including paracoccidioidomycosis in X-linked hyper-IgM syndrome, and the occurrence of BCG adverse reactions or other mycobacterial infections in patients with chronic granulomatous disease. Education in pediatric allergy and immunology is deficient for medical students, but residency programs are effective in training internists and pediatricians for the practice of allergy. The field of PID requires further training. Last, this review is a tribute to Prof. Dr. Charles Naspitz, one of the pioneers of our specialty in Brazil.

Evidence for postinitiation regulation of mRNA biogenesis in tuberculosis

Mycobacterium tuberculosis infection alters macrophage gene expression and macrophage response to IFN-γ, a critical host defense cytokine. However, regulation of these changes is poorly understood. We report discordance of changes in nascent transcript and total nuclear RNA abundance for the transcription factors STAT1 and IRF1, together with lack of effect on their RNA half-lives, in human THP-1 cells infected with M. tuberculosis and stimulated with IFN-γ. The results indicate that negative postinitiation regulation of mRNA biogenesis limits the expression of these factors, which mediate host defense against M. tuberculosis through the cellular response to IFN-γ. Consistent with the results for STAT1 and IRF1, transcriptome analysis reveals downregulation of postinitiation mRNA biogenesis processes and pathways by infection, with and without IFN-γ stimulation. Clinical relevance for regulation of postinitiation mRNA biogenesis is demonstrated by studies of donor samples showing that postinitiation mRNA biogenesis pathways are repressed in latent tuberculosis infection compared with cured disease and in active tuberculosis compared with ongoing treatment or with latent tuberculosis. For active disease and latent infection donors from two populations (London, U.K., and The Gambia), each analyzed using a different platform, pathway-related gene expression differences were highly correlated, demonstrating substantial specificity in the effect. Collectively, the molecular and bioinformatic analyses point toward downregulation of postinitiation mRNA biogenesis pathways as a means by which M. tuberculosis infection limits expression of immunologically essential transcription factors. Thus, negative regulation of postinitiation mRNA biogenesis can constrain the macrophage response to infection and overall host defense against tuberculosis.

Invasive fungal infections in patients with chronic granulomatous disease

Invasive fungal infections are a major threat for chronic granulomatous disease (CGD) patients. The present study provides a comprehensive overview of published invasive fungal infections in the CGD host through an extensive review of epidemiological, clinical, diagnostic and therapeutic data. In addition to the often mild clinical presentation, the currently used diagnostics for invasive aspergillosis have low sensitivity in CGD patients and cannot be easily translated to this non-neutropenic host. Aspergillus fumigatus and A. nidulans are the most commonly isolated species. A. nidulans infections are seldom reported in other immunocompromised patients, indicating a unique interaction between this fungus and the CGD host. The occurrence of mucormycosis is mainly noted in the setting of treatment of inflammatory complications with immunosuppressive drugs. Candida infections are infrequently seen and do not cause mucocutaneous disease but do show an age-dependent clinical presentation. The CGD patient is susceptible to a wide range of fungal pathogens, indicating the need to determine the causative fungus, often by invasive diagnostics, to guide optimal and rational treatment. This review summarizes current understanding of invasive fungal infections in patients with CGD and will serve as a starting point to guide optimal treatment strategies and to direct further research aimed at improving outcomes.

BAY 41-2272, a soluble guanylate cyclase agonist, activates human mononuclear phagocytes

BACKGROUND AND PURPOSE

Phagocyte function is critical for host defense against infections. Defects in phagocytic function lead to several primary immunodeficiencies characterized by early onset of recurrent and severe infections. In this work, we further investigated the effects of BAY 41-2272, a soluble guanylate cyclase (sGC) agonist, on the activation of human peripheral blood monocytes (PBM) and THP-1 cells.

EXPERIMENTAL APPROACH

THP-1 cells and PBM viability was evaluated by methylthiazoletetrazolium assay; reactive oxygen species production by lucigenin chemiluminescence; gene and protein expression of NAPDH oxidase components by qRT-PCR and Western blot analysis, respectively; phagocytosis and microbicidal activity by co-incubation, respectively, with zymosan and Escherichia coli; and cytokine release by elisa.

KEY RESULTS

BAY 41-2272, compared with the untreated group, increased spreading of monocytes by at least 35%, superoxide production by at least 50%, and gp91(PHOX) and p67(PHOX) gene expression 20 to 40 times, in both PBM and THP-1 cells. BAY 41-2272 also augmented phagocytosis of zymosan particles threefold compared with control, doubled microbicidal activity against E. coli and enhanced the release of TNF-α and IL-12p70 by both PBM and THP-1 cells. Finally, by inhibiting sGC with ODQ, we showed that BAY 41-2272-induced superoxide production and phagocytosis is not dependent exclusively on sGC activation.

CONCLUSIONS AND IMPLICATIONS

In addition to its ability to induce vasorelaxation and its potential application for therapy of vascular diseases, BAY 41-2272 was shown to activate human mononuclear phagocytes. Hence, it is a novel pro-inflammatory drug that may be useful for controlling infections in the immunocompromised host.

Advances in primary immunodeficiency diseases in Latin America: epidemiology, research, and perspectives

Primary immunodeficiencies (PIDs) are genetic disorders of the immune system comprising many different phenotypes. Although previously considered rare, recent advances in their clinical, epidemiological, and molecular definitions are revealing how much we still need to learn about them. For example, geographical and ethnic variations as well as the impact of certain practices influence their frequency and presentation, making it necessary to consider their study in terms of regions. The Latin American Society for Immunodeficiencies was established as an organization dedicated to provide scientific support for basic and clinical research and to develop tools and educational resources to promote awareness in the medical community. Initiatives such as these are positively influencing the way PIDs are tackled in these countries, as shown by recent reports and publications. This paper provides a historical compilation and a current view of the many issues faced by scientists studying these diseases in these countries, highlighting the diverse scientific contributions and offering a promising perspective for the further developments in this field in Latin America.

P67-phox (NCF2) lacking exons 11 and 12 is functionally active and leads to an extremely late diagnosis of chronic granulomatous disease (CGD)

Two brothers in their fifties presented with a medical history of suspected fungal allergy, allergic bronchopulmonary aspergillosis, alveolitis, and invasive aspergillosis and pulmonary fistula, respectively. Eventually, after a delay of 50 years, chronic granulomatous disease (CGD) was diagnosed in the index patient. We found a new splice mutation in the NCF2 (p67-phox) gene, c.1000+2T→G, that led to several splice products one of which lacked exons 11 and 12. This deletion was in frame and allowed for remarkable residual NADPH oxidase activity as determined by transduction experiments using a retroviral vector. We conclude that p67-phox which lacks the 34 amino acids encoded by the two exons can still exert considerable functional activity. This activity can partially explain the long-term survival of the patients without adequate diagnosis and treatment, but could not prevent progressing lung damage.

Autoimmune regulator (AIRE) contributes to Dectin-1-induced TNF-α production and complexes with caspase recruitment domain-containing protein 9 (CARD9), spleen tyrosine kinase (Syk), and Dectin-1

BACKGROUND

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) syndrome is a complex immunologic disease caused by mutation of the autoimmune regulator (AIRE) gene. Autoimmunity in patients with APECED syndrome has been shown to result from deficiency of AIRE function in transcriptional regulation of thymic peripheral tissue antigens, which leads to defective T-cell negative selection. Candidal susceptibility in patients with APECED syndrome is thought to result from aberrant adaptive immunity.

OBJECTIVE

To determine whether AIRE could function in anticandidal innate immune signaling, we investigated an extrathymic role for AIRE in the immune recognition of β-glucan through the Dectin-1 pathway, which is required for defense against Candida species.

METHODS

Innate immune signaling through the Dectin-1 pathway was assessed in both PBMCs from patients with APECED syndrome and a monocytic cell line. Subcellular localization of AIRE was assessed by using confocal microscopy.

RESULTS

PBMCs from patients with APECED syndrome had reduced TNF-α responses after Dectin-1 ligation but in part used a Raf-1-mediated pathway to preserve function. In the THP-1 human monocytic cell line, reducing AIRE expression resulted in significantly decreased TNF-α release after Dectin-1 ligation. AIRE formed a transient complex with the known Dectin-1 pathway components phosphorylated spleen tyrosine kinase and caspase recruitment domain-containing protein 9 after receptor ligation and localized with Dectin-1 at the cell membrane.

CONCLUSION

AIRE can participate in the Dectin-1 signaling pathway, indicating a novel extrathymic role for AIRE and a defect that likely contributes to fungal susceptibility in patients with APECED syndrome.

Interferons induce CXCR3-cognate chemokine production by human metastatic melanoma

Immune-mediated cancer regression requires tumor infiltration by antigen-specific effector T cells, but lymphocytes are commonly sparse in melanoma metastases. Activated T cells express CXCR3, whose cognate chemokines are CXCL9/MIG, CXCL10/IP-10, and CXCL11/I-TAC. Little is known about expression of these chemokines in lymph node (LN) metastases of melanoma. We evaluated whether metastatic melanoma induces these CXCR3-cognate chemokines in human LN-derived tissues. In addition, as these chemokines can be induced by interferon (IFN), we evaluated whether type I or II IFNs (IFN-α or IFN-γ, respectively) can modulate chemokine expression in an in vitro model of the human tumor microenvironment. Production of CXCL9-11 by melanoma-infiltrated nodes (MIN) was no different than tumor-free nodes; both produced less chemokine than activated LN (sentinel immunized nodes, SIN). These data suggest that melanoma infiltration into LN neither induces nor reduces CXCL9-11. Stimulation with IFN-α or IFN-γ increased production of CXCL10-11 from MIN, but not tumor-free node or SIN. IFN-γ also increased production of CXCL9 in MIN. In IFN-treated SIN, CD14+ cells were the primary source of CXCL9-11, whereas melanoma cells were the source of chemokine in MIN. Melanoma cells in MIN express IFN receptors. Consistent with these observations, multiple human melanoma lines expressed IFN receptors and produced CXCL9-11 in response to IFN treatment. Thus, melanoma infiltration of LN is insufficient to induce the production of CXCL9-11, but melanoma may be a significant source of IFN-induced chemokines. Collectively, these data suggest that IFN-α or IFN-γ may act in the tumor microenvironment to increase the chemotactic gradient for CXCR3+ T cells.

Hematologically important mutations: X-linked chronic granulomatous disease (third update)

Chronic granulomatous disease (CGD) is an immunodeficiency disorder affecting about 1 in 250,000 individuals. The disease is caused by a lack of superoxide production by the leukocyte enzyme NADPH oxidase. Superoxide is used to kill phagocytosed micro-organisms in neutrophils, eosinophils, monocytes and macrophages. The leukocyte NADPH oxidase is composed of five subunits, of which the enzymatic component is gp91-phox, also called Nox2. This protein is encoded by the CYBB gene on the X chromosome. Mutations in this gene are found in about 70% of all CGD patients. This article lists all mutations identified in CYBB in the X-linked form of CGD. Moreover, apparently benign polymorphisms in CYBB are also given, which should facilitate the recognition of future disease-causing mutations.

Essential role of nuclear factor-kappaB for NADPH oxidase activity in normal and anhidrotic ectodermal dysplasia leukocytes

This work investigated the functional role of nuclear factor-kappaB (NF-kappaB) in respiratory burst activity and in expression of the human phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase genes CYBB, CYBA, NCF1, and NCF2. U937 cells with a stably transfected repressor of NF-kappaB (IkappaBalpha-S32A/S36A) demonstrated significantly lower superoxide release and lower CYBB and NCF1 gene expression compared with control U937 cells. We further tested Epstein-Barr virus (EBV)-transformed B cells from patients with anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID), an inherited disorder of NF-kappaB function. Superoxide release and CYBB gene expression by EDA-ID cells were significantly decreased compared with healthy cells and similar to cells from patients with X-linked chronic granulomatous disease (X91(0) CGD). NCF1 gene expression in EDA-ID S32I cells was decreased compared with healthy control cells and similar to that in autosomal recessive (A47(0)) CGD cells. Gel shift assays demonstrated loss of recombinant human p50 binding to a NF-kappaB site 5' to the CYBB gene in U937 cells treated with NF-kappaB inhibitors, repressor-transfected U937 cells, and EDA-ID patients' cells. Zymosan phagocytosis was not affected by transfection of U937 cells with the NF-kappaB repressor. These studies show that NF-kappaB is necessary for CYBB and NCF1 gene expression and activation of the phagocyte NADPH oxidase in this model system.

Modern management of chronic granulomatous disease

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disorder of phagocytic cells resulting in failure to kill a characteristic spectrum of bacteria and fungi and in defective degradation of inflammatory mediators with concomitant granuloma formation. Current prophylaxis with trimethoprim-sulfamethoxazole, itraconazole and in selected cases additional interferon gamma is efficient, but imperfect. A significant recent progress towards new antibiotic (e.g. linezolid) and antifungal (e.g. voriconazole and posaconazole) therapy will allow survival of most patients into adulthood. Adolescent and adult CGD is increasingly characterized by inflammatory complications, such as granulomatous lung and inflammatory bowel disease, requiring immunosupressive therapy. Allogeneic haematopoietic stem cell transplantation from a human leucocyte antigen identical donor is currently the only proven curative treatment for CGD and can be offered to the selected patients. Gene-replacement therapy for patients lacking a suitable stem cell donor is still experimental and faces major obstacles and risks. However, it may offer some transitory benefits and has helped in a few cases to overcome life-threatening infections.

Up-regulation of NADPH oxidase components and increased production of interferon-gamma by leukocytes from sickle cell disease patients

We have previously demonstrated that mononuclear leukocytes from patients with sickle cell disease (SCD) release higher amounts of superoxide compared with normal controls. The aim of this study was to further study the NADPH oxidase system in these patients by investigating gene expression of NADPH oxidase components, phosphorylation of p47(phox) component, and the release of cytokines related to NADPH oxidase activation in mononuclear leukocytes from patients with SCD. gp91(phox) gene expression was significantly higher in monocytes from SCD patients compared with normal controls (P=0.036). Monocytes from SCD patients showed higher levels of p47(phox) phosphorylation compared with normal controls. INF-gamma release by lymphocytes from SCD patients was significantly higher compared with normal controls, after 48 h culture with phytohemagglutinin (P=0.02). The release of TNF-alpha by monocytes from SCD patients and normal controls was similar after 24 and 48 h culture with lipopolysaccharide (P>0.05). We conclude that monocytes from SCD patients show higher levels of gp91(phox) gene expression and p47(phox) phosphorylation, along with increased IFN-gamma release by SCD lymphocytes. These findings help to explain our previous observation showing the increased respiratory burst activity of mononuclear leukocytes from SCD patients and may contribute to inflammation and tissue damage in these patients.

Chronic granulomatous disease in pediatric patients: 25 years of experience

INTRODUCTION

Chronic granulomatous disease (CGD) is an uncommon primary immune deficiency (affecting 1/200,000 newborn infants) caused by a defect in phagocyte production of oxygen metabolites, and resulting in bacterial infections produced by catalase-positive microorganisms and fungal diseases that occasionally may prove fatal.

METHODS

A review is made of the clinical records of 13 pediatric patients diagnosed with CGD between 1980 and 2005.

RESULTS

All patients were males. The mean age at diagnosis was 36 months. The clinical manifestations at the time of diagnosis comprised the following: Abscesses or abscessified adenopathies 4/13 (Staphylococcus aureus (2), Serratia liquefaciens, S. marcescens and Klebsiella sp.), pneumonia 3/13 (Rhodococcus equi, Salmonella typhimurium plus Pneumocystis jiroveci), osteomyelitis 1/13 (Aspergillus sp.), sepsis 1/13 (S. aureus), urinary infection 1/13 (Klebsiella sp.), severe gastroenteritis 1/13, oral aphthae 1/13 and Crohn-like inflammatory bowel disease 1/13. The diagnosis was initially established by the nitroblue tetrazolium test, and confirmed by flow cytometry 10/13 and genetic techniques (gp91) 9/13. In the course of these disease processes there were 88 infections: abscesses (n = 26), lymphadenitis (n = 12), pneumoniae (n = 10), gastroenteritis (n = 7), sepsis (n = 6), osteomyelitis (n = 3) and others (n = 24). As to the germs isolated, the frequency distribution was as follows (n = 49): Aspergillus sp. (n = 10), Staphylococcus sp. (n = 7), Salmonella sp. (n = 6), Serratia sp. (n = 5), Pseudomonas aeruginosa (n = 4), Klebsiella sp. (n = 4), Proteus sp. (n = 3), Leishmania sp. (n = 2) and others (n = 8). IFN-gamma was administered in 7/13 cases, and itraconazole in 9/13; all received cotrimoxazole. There were four deaths, with one case each of sepsis due to gramnegative bacterial infection; disseminated aspergillosis; visceral leishmaniasis and hemophagocytosis; and post-kidney transplant complications.

CONCLUSIONS

Clinical suspicion and flow cytometry are the keys for diagnosis of CGD and detection of carrier relatives. Specific prophylactic measures and medical controls are required to prevent serious infections. IFN-gamma has been used intermittently, though its effectiveness is controversial.

[Two breakthroughs in CGD studies]

Studies in Chronic Granulomatous Disease showed two breakthroughs during this past decade. First, the discovery of 7 Nox/Duox family proteins, Noxo1 and Noxa1 (homologues of gp91(phox), p47(phox) and p67(phox)) may clarify novel physiological mechanisms for superoxide regulation in various organs, such as the regulation of blood pressure, mucosal defense system in respiratory/digestive tract and nephron. Secondly, the success in bone marrow transplantation and gene therapy for CGD should facilitate treatment for other genetic diseases as well.

Vasoactive intestinal peptide (VIP) prevents killing of virulent and phoP mutant Salmonella typhimurium by inhibiting IFN-γ stimulated NADPH oxidative pathways in murine macrophages

Vasoactive intestinal peptide is an immunomodulator with great potential in the treatment of inflammatory pathology. In this study, we have examined the effect of VIP on the growth dynamics of virulent Salmonella enterica. Serovar typhimurium (S. typhimurium) 14028 and 4/74 and an avirulent mutant (14028 phoP) in a murine, macrophage cell line (J774.2). In contrast to standard growth dynamics, in which phoP mutants do not survive in macrophages, we show that VIP (10(-10) M) significantly enhances phoP growth over a 24 h post-infection period even when the cells are co-cultured with IFN-gamma. We examined the effect of VIP on the generation of NADPH-induced reactive oxygen species (ROS) in Salmonella-infected/IFN-gamma cultured J774 cells. VIP inhibited gp91 mRNA levels, gp91 protein and subsequent ROS. The importance of ROS in killing of Salmonella by J774 cells was highlighted by experiments in which ROS production by J774 cells was inhibited using a conventional inhibitor, N-acetyl-L-cysteine captopril (ACC) and in which Salmonella growth significantly increased. Our findings suggest that although VIP inhibits inflammatory pathways in myeloid cells it also promotes the growth of avirulent (phoP) mutants.

Chronic Granulomatous Disease; fundamental stages in our understanding of CGD

It has been 50 years since chronic granulomatous disease was first reported as a disease which fatally affected the ability of children to survive infections. Various milestone discoveries from the insufficient ability of patients' leucocytes to destroy microbial particles to the underlying genetic predispositions through which the disease is inherited have had important consequences. Longterm antibiotic prophylaxis has helped to fight infections associated with chronic granulomatous disease while the steady progress in bone marrow transplantation and the prospect of gene therapy are hailed as long awaited permanent treatment options. This review unearths the important findings by scientists that have led to our current understanding of the disease.

Chronic granulomatous disease in Latin American patients: clinical spectrum and molecular genetics

BACKGROUND

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by early onset of recurrent and severe infections. The molecular defects causing CGD are heterogeneous and lead to absence, low expression, or malfunctioning of one of the phagocyte NADPH oxidase components. The aim of this study was to analyze the clinical features and to investigate the molecular genetic defects of Latin American patients with CGD.

PROCEDURES

The study included 14 patients. The diagnosis was based on a history of recurrent severe infections, impaired respiratory burst, and the demonstration of an underlying mutation by single strand conformation polymorphism (SSCP) or RT-PCR analysis, followed by genomic DNA or cDNA sequencing.

RESULTS

Seven unrelated patients were found to have the X-linked form of CGD (X-CGD). Heterogeneous mutations affected the CYBB gene: two insertions, one substitution, and four splice site defects; two of them are novel. Seven patients presented with one of the autosomal recessive forms of CGD (A47-CGD); all had the most common mutation, a DeltaGT deletion in exon 2 of the NCF1 gene. Pneumonia was the most frequent clinical feature, followed by pyoderma, sinusitis, otitis, and liver abscess. Patients with X-CGD were more likely to have initial infections before age 2 years and to have inflammatory obstructive granulomas later. None of the patients had severe adverse reactions to BCG immunization.

CONCLUSIONS

X-CGD patients from Latin America showed a high degree of molecular heterogeneity, including two novel mutations. Their clinical characteristics included early onset of infections and eventual obstructive granulomas. A47-CGD represented 50% of the reported cases, a higher prevalence than reported in other series.

Stimulation of gp91 phagocytic oxidase and reactive oxygen species in neutrophils by an avirulent Salmonella enterica serovar infantis strain protects gnotobiotic piglets from lethal challenge with serovar Typhimurium strain F98 without inducing intestinal pathology

Preinoculation of susceptible 5-day-old gnotobiotic piglets with Salmonella enterica serovar Infantis strain 1326/28Phi(r) stimulates neutrophil migration into the intestine, which rapidly protects the pigs against a subsequent (normally lethal) challenge with S. enterica serovar Typhimurium strain F98. Here we show that inoculation with either 1326/28Phi(r) or F98 activated reactive oxygen species (ROS) in neutrophils via NADPH pathways in vivo and in vitro and that the survival of both Salmonella strains was increased if neutrophils were cocultured with the ROS inhibitor N-acetylcysteine (captopril). Neither F98 nor 1326/28Phi(r) significantly increased reactive nitrogen species (RNS) levels in neutrophils isolated from uninfected pigs. Our results indicate the following: (i) rapid protection of highly susceptible gnotobiotic piglets against F98-induced gastroenteritis by preinoculation with 1326/28Phi(r) is likely to be due to stimulation of ROS-producing neutrophils in the intestinal epithelium prior to challenge with the lethal strain; (ii) pathological lesions of the intestine during severe gastroenteritis are not necessarily induced by neutrophil migration per se; and (iii) if neutrophil migration into the intestine is responsible for pathology, then neither increased production of ROS or RNS (in pigs inoculated with the lethal strain) nor reduced production (in protected pigs in which pathological lesions are ameliorated by preinoculation with 1326/28Phi(r)) can account for this phenomenon.

Anaplasma phagocytophilum modulates gp91phox gene expression through altered interferon regulatory factor 1 and PU.1 levels and binding of CCAAT displacement protein

Infection of neutrophil precursors with Anaplasma phagocytophilum, the causative agent of human granulocytic ehrlichiosis, results in downregulation of the gp91(phox) gene, a key component of NADPH oxidase. We now show that repression of gp91(phox) gene transcription is associated with reduced expression of interferon regulatory factor 1 (IRF-1) and PU.1 in nuclear extracts of A. phagocytophilum-infected cells. Loss of PU.1 and IRF-1 correlated with increased binding of the repressor, CCAAT displacement protein (CDP), to the promoter of the gp91(phox) gene. Reduced protein expression of IRF-1 was observed with or without gamma interferon (IFN-gamma) stimulation, and the defect in IFN-gamma signaling was associated with diminished binding of phosphorylated Stat1 to the Stat1 binding element of the IRF-1 promoter. The diminished levels of activator proteins and enhanced binding of CDP account for the transcriptional inhibition of the gp91(phox) gene during A. phagocytophilum infection, providing evidence of the first molecular mechanism that a pathogen uses to alter the regulation of genes that contribute to an effective respiratory burst.

Human neutrophils produce interferon gamma upon stimulation by interleukin-12

Interferon gamma (IFNgamma) is a Th1 cytokine mainly produced by T cells, NK cells and macrophages in response to interleukin (IL)-12. As polymorphonuclear neutrophils (PMN) have been shown to produce and to release numerous cytokines, in particular upon IL-12 stimulation, we investigated the ability of highly purified PMN to secrete IFNgamma. We found that PMN contained a small store of IFNgamma, and that this store was rapidly secreted upon stimulation by degranulating agents such as formyl peptides. Moreover, after a few hours of stimulation with appropriate agents, PMN synthesized IFNgamma. The effect of IL-12 was time- and concentration-dependent, and IL-12 combinations with IL-2, IL-15, IL-18 or LPS were highly synergistic. Cycloheximide inhibited IFNgamma release in such optimal conditions, confirming the ability of PMN to synthesize IFNgamma. IFNgamma synthesis was associated with an increase in specific mRNA content, pointing to a transcriptional mechanism. The IFNgamma produced by PMN was biologically active, as demonstrated by its ability to induce TNFalpha synthesis by PMN themselves or to induce IL-10 synthesis by peripheral blood mononuclear cells. These findings reveal a novel pathway of autocrine and paracrine PMN activation. They also identified a new role for IFNgamma, bridging innate and adaptive immune responses.

The effect of IFN-gamma and TNF-alpha on the eosinophilic differentiation and NADPH oxidase activation of human HL-60 clone 15 cells

The aim of this study was to investigate the effect of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) on NADPH oxidase activity and gp91-phox gene expression in HL-60 clone 15 cells as they differentiate along the eosinophilic lineage. The results were compared to the eosoniphilic inducers interleukin-5 (IL-5) and butyric acid. IFN-gamma (100 U/ml) and TNF-alpha (1000 U/ml) or IL-5 (200 pM) caused a significant increase in the expression of the eosinophil peroxidase (EPO) and the major basic protein (MBP) genes. Similar results were observed when the cells were cultured with 0.5 mM butyric acid for 5 days. IFN-gamma (100 U/ml) and TNF-alpha (1000 U/ml) also caused a significant increase in superoxide release by HL-60 clone 15 cells after 2 days compared with control or with butyric acid-induced cells. After 5 days, these cytokines and butyric acid induced an even stronger release of superoxide. HL-60 clone 15 cells cultured with IFN-gamma and TNF-alpha for 2 days showed a significant increase in gp91-phox gene expression. We conclude that IFN-gamma and TNF-alpha are sufficient to induce the differentiation of HL-60 clone 15 cells to the eosinophilic lineage and to upregulate gp91-phox gene expression and activity of the NADPH oxidase system.

NOX-2S is a new member of the NOX family of NADPH oxidases

A novel isoform of the NOX-2 subunit of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase has been identified using expressed sequence tag (EST) database mining. The novel isoform, NOX-2S, is a splice variant of NOX-2 and includes a previously unidentified exon, mapped 6.4 kb downstream of exon III, and encodes an in-frame stop codon generating a predicted truncated protein of approximately 12.7 kDa, the smallest reported member of the NOX family. Thus, NOX-2S is predicted to have only two transmembrane domains, however, the new C-terminal sequence includes two new potential protein kinase C (PKC) phosphorylation sites. Expression of NOX-2S mRNA was detected in many mouse tissues, and several human cell lines including the myeloid cell line HL-60, and the B cell line Ramos, indicating that the splice variant is conserved in mouse and man. NOX-2S is found co-expressed together with NOX-2 in all of the tissues and cells under investigation, both nonphagocytic and phagocytic. Induction of the myeloid cell line HL-60 into the neutrophil phagocytic lineage by dimethyl sulphoxide (DMSO), led to a marked increase in NOX-2S and NOX-2 expression in the myelocyte rather than promyelocyte stages of differentiation. Furthermore, in the B-cell line Ramos, differentiated with the cytokine interferon-gamma (IFN-gamma), splicing was altered to increase NOX-2S mRNA generation over NOX-2. Here we have identified NOX-2S, the first reported normally occurring splice variant of NOX-2. The sequence identity between mouse and human NOX-2S strongly implies conservation in function and possibly a role for NOX-2S in the regulation of NADPH oxidase activity.

The use of reverse transcription-PCR for the diagnosis of X-linked chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited disorder of the innate immune system characterized by a defective oxidative burst of phagocytes and subsequent impairment of their microbicidal activity. Mutations in one of the NADPH-oxidase components affect gene expression or function of this system, leading to the phenotype of CGD. Defects in gp91-phox lead to X-linked CGD, responsible for approximately 70% of CGD cases. Investigation of the highly heterogeneous genotype of CGD patients includes mutation analysis, Northern blot or Western blot assays according to the particular case. The aim of the present study was to use reverse transcription (RT)-PCR for the analysis of molecular defects responsible for X-linked CGD in eight Brazilian patients and to assess its potential for broader application to molecular screening in CGD. Total RNA was prepared from Epstein B virus-transformed B-lymphocytes and reverse transcribed using random hexamers. The resulting cDNA was PCR-amplified by specific and overlapping pairs of primers designed to amplify three regions of the gp91-phox gene: exons 1-5, 3-9, and 7-13. This strategy detected defective gp91-phox expression in seven patients. The RT-PCR results matched clinical history, biochemical data (nitroblue tetrazolium or superoxide release assay) and available mutation analysis in four cases. In three additional cases, RT-PCR results matched clinical history and biochemical data. In another case, RT-PCR was normal despite a clinical history compatible with CGD and defective respiratory burst. We conclude that this new application of RT-PCR analysis--a simple, economical and rapid method--was appropriate for screening molecular defects in 7 of 8 X-linked CGD patients.

Association of glucose-6-phosphate dehydrogenase deficiency and X-linked chronic granulomatous disease in a child with anemia and recurrent infections

Patients with severe leukocyte G6PD deficiency may present with impairment of NADPH oxidase activity and a history of recurrent infections, mimicking the phenotype of chronic granulomatous disease. We report herein a child with recurrent infections who initially received the diagnosis of G6PD deficiency. His erythrocyte G6PD activity was reduced: 1.8 U/g Hb (normal: 12.1 +/- 2.1 U/g Hb). Further studies revealed that G6PD activity in neutrophils, mononuclear leukocytes, and Epstein-Barr virus-transformed B-lymphocytes from the proband was similar to healthy controls. Molecular studies showed that the G6PD deficiency was due a 202 G-->A mutation, the A- variant common in African ethnic groups. The proband also exhibited severely impaired respiratory burst activity, as observed in X-linked CGD. Sequence analysis of genomic DNA showed a 264 G-->A substitution at the 3' splice junction of gp91-phox exon 3. The cDNA sequence showed a deletion of gp91-phox exon 3, giving rise to an unstable or nonfunctional mutant gp91-phox and to the phenotype of X-linked CGD. We propose that clinicians treating a patient with G6PD deficiency during a severe infection episode consider the possibility of temporary or permanent impairment of the phagocytes' microbicidal activity and the eventual association of G6PD deficiency and chronic granulomatous disease.

Posttranscriptional Inhibition of Gene Expression byMycobacterium tuberculosisOffsets Transcriptional Synergism with IFN-γ and Posttranscriptional Up-Regulation by IFN-γ

Host defense against Mycobacterium tuberculosis requires the cytokine IFN-gamma and IFN regulatory factor 1 (IRF-1), a transcription factor that is induced to high levels by IFN-gamma. Therefore, we chose to study regulation of IRF-1 expression as a model for effects of M. tuberculosis on response to IFN-gamma. We found that IRF-1 mRNA abundance increased far more than transcription rate in human monocytic THP-1 cells stimulated by IFN-gamma, but less than transcription rate in cells infected by M. tuberculosis. IFN-gamma stimulation of infected cells caused a synergistic increase in IRF-1 transcription, yet IRF-1 mRNA abundance was similar in uninfected and infected cells stimulated by IFN-gamma, as was the IRF-1 protein level. Comparable infection by Mycobacterium bovis bacillus Calmette-Guérin failed to induce IRF-1 expression and had no effect on the response to IFN-gamma. We also examined the kinetics of transcription, the mRNA t(1/2), and the distribution of IRF-1 transcripts among total nuclear RNA, poly(A) nuclear RNA, and poly(A) cytoplasmic RNA pools in cells that were infected by M. tuberculosis and/or stimulated by IFN-gamma. Our data suggest that infection by M. tuberculosis inhibits RNA export from the nucleus. Moreover, the results indicate that regulated entry of nascent transcripts into the pool of total nuclear RNA affects IRF-1 expression and that this process is stimulated by IFN-gamma and inhibited by M. tuberculosis. The ability of infection by M. tuberculosis to limit the increase in IRF-1 mRNA expression that typically follows transcriptional synergism may contribute to the pathogenicity of M. tuberculosis.

Chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency that affects phagocytes of the innate immune system and is characterized by a greatly increased susceptibility to severe bacterial and fungal infections. CGD is caused by mutations in any one of four genes that encode the subunits of phagocyte NADPH oxidase, the enzyme that generates microbicidal (and pro-inflammatory) oxygen radicals. Of the 410 CGD mutations identified, 95% cause the complete or partial loss of protein and provide little information regarding the relationship between protein structure and function. The remaining 5%, however, result in normal levels of inactive protein and many have provided valuable insights into the function of affected subunits and their roles in oxidase regulation and catalysis. Moreover, recent CGD studies have revealed that recombination events between the p47-phox gene (NCF-1) and its pseudogenes not only cause the absence of p47-phox, but also predict the generation of a novel fusion protein.

Induction of antimicrobial pathways during early-phase immune response to Salmonella spp. in murine macrophages: gamma interferon (IFN-gamma) and upregulation of IFN-gamma receptor alpha expression are required for NADPH phagocytic oxidase gp91-stimulated oxidative burst and control of virulent Salmonella spp

The effect of gamma interferon (IFN-gamma) on elevation of reactive oxygen species and the viability of virulent wild-type and avirulent mutants of Salmonella enterica serovar Typhimurium and S. enterica serovar Infantis was studied in a murine macrophage cell line (J774.2 cells). S. enterica serovar Typhimurium 14028 phoP and a rough lipopolysaccharide mutant of S. enterica serovar Infantis 1326/28 (phi(r)) (avirulent mutants) induced NADPH phagocytic oxidase gp91 (gp91(phox)) activity and a significant (P < 0.05) elevation of reactive oxygen species within 12 h without coculture with IFN-gamma. This coincided with reduced survival of S. enterica serovar Typhimurium14028 phoP or stasis of S. enterica serovar Infantis phi(r). Fluorometric studies indicated that expression of IFN-gamma on infected J774.2 cells was not significantly (P > 0.05) elevated. However, studies with the virulent S. enterica serovar Typhimurium strains showed that a comparable level of control of bacterial numbers could only be achieved by coculture with IFN-gamma. This coincided with significant upregulation of IFN-gamma receptor alpha expression on the surface of J774.2 cells and was completely abolished by N-acetyl-L-cysteine captopril (an inhibitor of reactive oxygen species). Delay in reactive oxygen species induction due to a requirement for IFN-gamma and upregulation of IFN-gamma receptor alpha in macrophages infected with virulent salmonellae may result in greater dissemination of virulent salmonellae in host tissue.

Current treatment options for chronic granulomatous disease

Chronic granulomatous disease is a rare inherited disorder of phagocytic cells which results in a susceptibility to infections of catalase-positive bacteria and fungi (especially Aspergillus species), as well as granuloma formation. The mainstay of therapy is antibacterial and antifungal prophylaxis. Trimethoprim sulfamethoxazole is the drug of choice for the prevention of bacterial infection, while itraconazole is most widely used for the prevention of fungal infection. Immunomodulatory agents, such as IFN-phi, have a role in the prevention and treatment of intractable infection. New antifungal agents provide the promise of improved cure rates for invasive Aspergillus, while bone marrow transplants and gene therapy may offer the promise of complete cure.