IFN-gamma is effective in reducing infections in the mouse model of chronic granulomatous disease (CGD)

Prevention of Infectious Complications in Patients With Chronic Granulomatous Disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency that confers a markedly increased risk of bacterial and fungal infections caused by certain opportunistic pathogens. Current evidence supports the use of prophylactic antibacterial, antifungal, and immunomodulatory therapies designed to prevent serious or life-threatening infections in patients with CGD. In this review, we discuss current strategies for the prevention of infections in children and adults with CGD and the evidence that supports those strategies. In addition, we address current challenges and opportunities for future research in this important area.

Chronic granulomatous disease as an SOS call for multicenter cooperative effort to prevent infections: A meta-analysis of the treatments

BACKGROUND

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disease. Patients with CGD experience recurrent life-threatening infections. Lack of large interventional trials generated several doubts for the treatment of infections in CGD.

OBJECTIVE

To evaluate the effect of interferon gamma, antifungal drugs, and antibiotics in patients with CGD undergoing prophylaxis of infections.

METHODS

A meta-analysis of the interventional trials was performed. The studies were identified by searching MEDLINE, ISI Web of Science, SCOPUS, and Cochrane database. The last search was run on January 2016. Reference lists of all studies included in the present systematic review were screened for potential additional eligible studies.

RESULTS

Two studies with 163 patients with CGD were included in the interferon gamma analysis. Severe infections occurred in 17 of 73 patients (23%) treated with interferon gamma and in 49 of 90 patients (54%) not undergoing treatment with interferon gamma. Compared with control, severe infections were significantly reduced in patients treated with interferon gamma (relative risk, 0.46; 95% confidence interval, 0.29-0.73; P = .001). Interferon gamma treatment was associated with an absolute risk reduction of 31% and a number needed to treat of 3. Furthermore, compared with control, interferon gamma treatment reduced pulmonary infections (relative risk, 0.43; 95% confidence interval, 0.19-0.96; P = .04). Two studies with 172 patients with CGD were included in the antifungal drug analysis. Infections occurred in 4 of 69 patients (6%) treated with antifungals and in 17 of 103 patients (16%) not receiving treatment with antifungals. Compared with control, Aspergillus infections were not significantly reduced in patients treated with antifungals. No randomized prospective clinical trials of antibacterial prophylaxis in patients with CGD have been performed.

CONCLUSION

Despite the fact that interferon gamma prophylaxis seems to have a positive effect on severe infections, small sample sizes preclude definite conclusions. Further trials with interferon gamma and/or antifungal and antibiotics are necessary to optimize the treatment of CGD.

In vitro interferon γ improves the oxidative burst activity of neutrophils in patients with chronic granulomatous disease with a subtype of gp91phox deficiency

AIM OF THIS STUDY

Chronic granulomatous disease (CGD) is a genetically heterogeneous primary immunodeficiency caused by a defect in phagocyte production of oxygen metabolites, and resulting in infections produced by catalase-positive microorganisms and fungi. Interferon γ (IFN-γ) has a multitude of effects on the immune system. Although preliminary studies with CGD patients on treatment with IFN-γ showed that it enhanced phagocytosis and superoxide production, ongoing studies did not reveal a significant increase of this function. Here we investigated the oxidative capacity of phagocytes in different subtypes of CGD patients on treatment with IFN-γ in vitro.

MATERIAL AND METHODS

Fifty-seven patients with CGD from 14 immunology centres were enrolled to our multi-centre study. Twenty-one patients were studied as controls. Oxidative burst assay with dihydrorhodamine 123 (DHR) was used and the stimulation index (SI) was calculated with respect to CGD subtypes in both neutrophils and monocytes before, and then one and 24 hours after adding IFN-γ.

RESULTS

Upon comparison of the SIs of the patients' neutrophils before in vitro IFN-γ at hour 0, and after adding IFN-γ at hour 1 and 24 were compared, and the differences were determined between hours 0-24 and hours 1-24. This difference was especially apparent between hours 1-24. In CGD subtypes, particularly in gp91phox subtype, it was seen that, following in vitro IFN-γ, SIs of neutrophils began to increase after hour 1, and that increase became more apparent at hour 24.

CONCLUSIONS

Our study showed that IFN-γ treatment may increase the oxidative bursting activity by increasing the superoxide production in neutrophils, particularly in gp91phox subtype.

Chronic granulomatous disease

Chronic granulomatous disease (CGD) is a paradigm for nonlymphoid primary immune defects, and has guided elucidation of oxygen metabolism in the phagocyte, vasculature, and brain. It has been in the forefront of the development of antimicrobial prophylaxis before the advent of advanced HIV and before its routine use in neutropenia. It has been an attractive target for gene therapy and bone marrow transplantation for nonmalignant diseases. Therefore, CGD is worthy of attention for its historical interest and because it is a disease for which expert management is imperative.

Animal models of human granulocyte diseases

In vivo animal models have proven very useful to the understanding of basic biologic pathways of the immune system, a prerequisite for the development of innovate therapies. This article addresses currently available models for defined human monogenetic defects of neutrophil granulocytes, including murine, zebrafish, and larger mammalian species. Strengths and weaknesses of each system are summarized, and clinical investigators may thus be inspired to develop further lines of research to improve diagnosis and therapy by use of the appropriate animal model system.

A negative role for MyD88 in the resistance to starvation as revealed in an intestinal infection of Drosophila melanogaster with the Gram-positive bacterium Staphylococcus xylosus

Drosophila melanogaster is a useful model to investigate mucosal immunity. The immune response to intestinal infections is mediated partly by the Immune deficiency (IMD) pathway, which only gets activated by a type of peptidoglycan lacking in several medically important Gram-positive bacterial species such as Staphylococcus. Thus, the intestinal host defense against such bacterial strains remains poorly known. Here, we have used Staphylococcus xylosus to develop a model of intestinal infections by Gram-positive bacteria. S. xylosus behaves as an opportunistic pathogen in a septic injury model, being able to kill only flies immunodeficient either for the Toll pathway or the cellular response. When ingested, it is controlled by IMD-independent host intestinal defenses, yet flies eventually die. Having excluded an overreaction of the immune response and the action of toxins, we find that flies actually succumb to starvation, likely as a result of a competition for sucrose between the bacteria and the flies. Fat stores of wild-type flies are severely reduced within a day, a period when sucrose is not yet exhausted in the feeding solution. Interestingly, the Toll pathway mutant MyD88 is more resistant to the ingestion of S. xylosus and to starvation than wild-type flies. MyD88 flies do not rapidly deplete their fat stores when starved, in contrast to wild-type flies. Thus, we have uncovered a novel function of MyD88 in the regulation of metabolism that appears to be independent of its known roles in immunity and development.

Interferon-gamma induced adipose tissue inflammation is linked to endothelial dysfunction in type 2 diabetic mice

Interferon-gamma (IFNγ) has previously been associated with immuno-mediated inflammation in diet-induced obesity and type 1 diabetes. This study sought to define the role of IFNγ-induced adipose tissue inflammation in endothelial dysfunction in type 2 diabetes. We examined mesenteric adipose tissue (MAT) inflammation, and endothelial function of small mesenteric artery (SMA) in control mice (m Lepr(db)), diabetic mice (Lepr(db)), m Lepr(db) treated with IFNγ, and Lepr(db) treated with anti-IFNγ or anti-monocyte chemoattractant protein-1 (anti-MCP-1). mRNA and protein expression of IFNγ and MCP-1 were increased in MAT of Lepr(db), accompanied by increased T-lymphocyte and macrophage infiltration. Anti-IFNγ reduced MAT inflammatory cell infiltration and inflammatory cytokine expression in Lepr(db), while IFNγ treatment showed the opposite effects in m Lepr(db). Acetylcholine (ACh)-induced vasorelaxation of SMA was impaired in Lepr(db) versus m Lepr(db), but sodium nitroprusside (SNP)-induced vasorelaxation was comparable. Both anti-IFNγ and anti-MCP-1 improved endothelial function of Lepr(db), while IFNγ treatment impaired endothelial function of m Lepr(db). Superoxide production was higher in both MAT and SMA of Lepr(db) mice, and anti-IFNγ reduced MAT and SMA superoxide production. Macrophage accumulation in the adventitia of SMA, and mRNA expression of MCP-1 in SMA were increased in Lepr(db) and IFNγ-treated m Lepr(db), but reduced in anti-IFNγ treated Lepr(db). These findings suggest IFNγ has a key role in the regulation of visceral adipose tissue inflammatory response and endothelial dysfunction in type 2 diabetes.

Bariatric surgery reduces visceral adipose inflammation and improves endothelial function in type 2 diabetic mice

OBJECTIVE

Bariatric surgery is emerging as an effective method to alleviate a multitude of medical conditions associated with morbid obesity and type 2 diabetes. However, little is known about the effects and mechanisms of bariatric surgery on visceral fat inflammation and endothelial dysfunction in type 2 diabetes. We hypothesize that bariatric surgery ameliorates interferon-γ-mediated adipose tissue inflammation/oxidative stress and improves endothelial function in type 2 diabetic mice.

METHODS AND RESULTS

Control mice (m Lepr(db)) and diabetic mice (Lepr(db)) were treated with either sham surgery or improved gastric bypass surgery and then were evaluated at 5, 10, 20, and 30 days to assess postsurgical effects. Surgery reduced body weight, abdominal adiposity, blood glucose level, and food intake in Lepr(db). The surgery-induced decrease in visceral adiposity was accompanied by amelioration of T-lymphocytes and macrophage infiltration, as well as reduction in the expression of interferon-γ and other inflammatory cytokines in the mesenteric adipose tissue (MAT) of Lepr(db) mice. Furthermore, surgery improved endothelium-dependent, but not endothelium-independent, vasorelaxation in small mesenteric arteries (SMA) of Lepr(db) mice. The improvement in endothelial function was largely attenuated by nitric oxide synthase inhibitor (L-NAME) incubation. Interferon-γ treatment increased the mRNA expression of tumor necrosis factor-α in the MAT of control mice and incubation of SMA of control mice with tumor necrosis factor-α caused impairment of endothelial function. Superoxide production in MAT/SMA and nitrotyrosine protein level in SMA were elevated in diabetic mice. Surgery reduced MAT/SMA oxidative stress in Lepr(db) mice.

CONCLUSIONS

The amelioration of adipose tissue inflammation and the improvement of endothelial function may represent important mechanisms that result in cardiovascular benefits after bariatric surgery.

Impaired phagocytosis of apoptotic cells by macrophages in chronic granulomatous disease is reversed by IFN-γ in a nitric oxide-dependent manner

Immunodeficiency in chronic granulomatous disease (CGD) is well characterized. Less understood are exaggerated sterile inflammation and autoimmunity associated with CGD. Impaired recognition and clearance of apoptotic cells resulting in their disintegration may contribute to CGD inflammation. We hypothesized that priming of macrophages (Ms) with IFN-γ would enhance impaired engulfment of apoptotic cells in CGD. Diverse M populations from CGD (gp91(phox)(-/-)) and wild-type mice, as well as human Ms differentiated from monocytes and promyelocytic leukemia PLB-985 cells (with and without mutation of the gp91(phox)), demonstrated enhanced engulfment of apoptotic cells in response to IFN-γ priming. Priming with IFN-γ was also associated with increased uptake of Ig-opsonized targets, latex beads, and fluid phase markers, and it was accompanied by activation of the Rho GTPase Rac. Enhanced Rac activation and phagocytosis following IFN-γ priming were dependent on NO production via inducible NO synthase and activation of protein kinase G. Notably, endogenous production of TNF-α in response to IFN-γ priming was critically required for inducible NO synthase upregulation, NO production, Rac activation, and enhanced phagocytosis. Treatment of CGD mice with IFN-γ also enhanced uptake of apoptotic cells by M in vivo via the signaling pathway. Importantly, during acute sterile peritonitis, IFN-γ treatment reduced excess accumulation of apoptotic neutrophils and enhanced phagocytosis by CGD Ms. These data support the hypothesis that in addition to correcting immunodeficiency in CGD, IFN-γ priming of Ms restores clearance of apoptotic cells and may thereby contribute to resolution of exaggerated CGD inflammation.

Chronic granulomatous disease

Chronic granulomatous disease (CGD) was first described in the 1950s and has become a paradigm for genetic neutrophil diseases. It is characterized by recurrent infections with a narrow spectrum of bacteria and fungi as well as a common set of inflammatory complications most notably including inflammatory bowel disease. Over the last half century major advances in management have profoundly altered the major clinical issues and the life expectancy of CGD. With X-linked and autosomal recessive forms, it has been an important disease for the development of bone marrow transplantation and gene therapy. Some of the recent developments in infectious syndromes, inflammatory complications, and curative approaches are discussed in this review.

RNA oxidation and zinc in hepatic encephalopathy and hyperammonemia

Hepatic encephalopathy is a neuropsychiatric manifestation of acute and chronic liver failure. Ammonia plays a key role in the pathogenesis of hepatic encephalopathy by inducing astrocyte swelling and/or sensitizing astrocytes to swelling by a heterogeneous panel of precipitating factors and conditions. Whereas astrocyte swelling in acute liver failure contributes to a clinically overt brain edema, a low grade glial edema without clinically overt brain edema is observed in hepatic encephalopathy in liver cirrhosis. Astrocyte swelling produces reactive oxygen and nitrogen oxide species (ROS/RNOS), which again increase astrocyte swelling, thereby creating a self-amplifying signaling loop. Astroglial swelling and ROS/RNOS increase protein tyrosine nitration and may account for neurotoxic effects of ammonia and other precipitants of hepatic encephalopathy. Recently, RNA oxidation and an increase of free intracellular zinc ([Zn(2+)](i)) were identified as further consequences of astrocyte swelling and ROS/RNOS production. An elevation of [Zn(2+)](i) mediates mRNA expression of metallothionein and the peripheral benzodiazepine receptor (PBR) induced by hypoosmotic astrocyte swelling. Further, Zn(2+) mediates RNA oxidation in ammonia-treated astrocytes. In the brain of hyperammonemic rats oxidized RNA localizes in part to perivascular astrocyte processes and to postsynaptic dendritic spines. RNA oxidation may impair postsynaptic protein synthesis, which is critically involved in learning and memory consolidation. RNA oxidation offers a novel explanation for multiple disturbances of neurotransmitter systems and gene expression and the cognitive deficits observed in hepatic encephalopathy.

ROS-deficient monocytes have aberrant gene expression that correlates with inflammatory disorders of chronic granulomatous disease

Chronic granulomatous disease is an immunodeficiency caused by an inability to produce reactive oxygen species. While the mechanism of hyper-sensitivity to infection is well understood in CGD, the basis for debilitating inflammatory disorders that arise in the absence of evident infection has not been fully explained. Herein it is demonstrated that resting and TLR-activated monocytes from individuals with CGD expressed significantly higher levels of inflammatory mediators than control cells; the expression in CGD cells resembled normal cells stimulated with lipopolysaccharide. The lack of acute illness, infection or circulating endotoxin in the blood of the CGD patients at the time of sampling was consistent with infection-free inflammation. The enhanced expression of inflammatory mediators correlated with elevated expression of NF-kappaB and was dependent on ERK1/2 signalling. The results are consistent with the hypothesis that ROS are anti-inflammatory mediators that control gene expression and potentially limit the development of sterile inflammatory disorders.

Susceptibility to mycobacterial infections in children with X-linked chronic granulomatous disease: a review of 17 patients living in a region endemic for tuberculosis

BACKGROUND

Chronic granulomatous disease (CGD) is a rare disorder of phagocytic oxidative bursts leading to recurrent pyogenic infections. Affected individuals are most prone to infections caused by staphylococci, Salmonella, Candida, and Aspergillus, but previously we observed a high incidence of Mycobacterium tuberculosis infection in Chinese children with CGD.

OBJECTIVE

To determine the spectrum of infections in patients with X-linked CGD, with an emphasis on mycobacterial infections, and to review all CYBB gene mutations identified in our center.

RESULTS

From 1988 to 2005, 17 Chinese male children were diagnosed to have X-linked CGD. Fifteen mutations were identified, including 3 splice site defects (IVS1-1G>C, 266G>A, IVS3-1G>A), 5 missense mutations (591T>C, 627T>A, 949T>A, 1039T>A, 1512G>C), 3 nonsense mutations (882C>T, 1451C>A, 1569G>T), 1 insertion (756_757insA), and 3 deletions (660_662delTTC, 727delT, 1341delT). Eight of these were novel mutations. Recurrent pneumonia, lymphadenitis, and bacterial skin abscess were the commonest types of infection. Seven patients had tuberculosis (TB). Seven patients had prolonged scarring or abscess formation at the Calmette-Guérin bacillus (BCG) injection site, and 1 had disseminated BCG infection. Three patients had pulmonary aspergillosis. Four patients underwent hemopoietic stem cell transplantation, but 2 died of complications.

CONCLUSIONS

Patients with CGD are susceptible to TB and BCG complications. Our observation suggests that oxidative burst is probably important in host defense against mycobacterial infections. Because interferon-gamma is the key cytokine involved in mycobacterial immunity, there may be a stronger indication for its use in CGD patients living in areas endemic for TB.

Defective tryptophan catabolism underlies inflammation in mouse chronic granulomatous disease

Half a century ago, chronic granulomatous disease (CGD) was first described as a disease fatally affecting the ability of children to survive infections. Various milestone discoveries have since been made, from an insufficient ability of patients' leucocytes to kill microbes to the underlying genetic abnormalities. In this inherited disorder, phagocytes lack NADPH oxidase activity and do not generate reactive oxygen species, most notably superoxide anion, causing recurrent bacterial and fungal infections. Patients with CGD also suffer from chronic inflammatory conditions, most prominently granuloma formation in hollow viscera. The precise mechanisms of the increased microbial pathogenicity have been unclear, and more so the reasons for the exaggerated inflammatory response. Here we show that a superoxide-dependent step in tryptophan metabolism along the kynurenine pathway is blocked in CGD mice with lethal pulmonary aspergillosis, leading to unrestrained Vgamma1(+) gammadelta T-cell reactivity, dominant production of interleukin (IL)-17, defective regulatory T-cell activity and acute inflammatory lung injury. Although beneficial effects are induced by IL-17 neutralization or gammadelta T-cell contraction, complete cure and reversal of the hyperinflammatory phenotype are achieved by replacement therapy with a natural kynurenine distal to the blockade in the pathway. Effective therapy, which includes co-administration of recombinant interferon-gamma (IFN-gamma), restores production of downstream immunoactive metabolites and enables the emergence of regulatory Vgamma4(+) gammadelta and Foxp3(+) alphabeta T cells. Therefore, paradoxically, the lack of reactive oxygen species contributes to the hyperinflammatory phenotype associated with NADPH oxidase deficiencies, through a dysfunctional kynurenine pathway of tryptophan catabolism. Yet, this condition can be reverted by reactivating the pathway downstream of the superoxide-dependent step.

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.

Recombinant interferon γ1b immune enhancement in 20 patients with hematologic malignancies and systemic opportunistic infections treated with donor granulocyte transfusions

BACKGROUND

The response to antifungal therapy alone often is suboptimal in patients with cancer who have therapy-refractory neutropenia, and even donor-derived granulocyte transfusions (GTX) are not always successful. The authors evaluated the safety and efficacy of immune enhancement using recombinant interferon gamma1b (rIFN-gamma1b) in patients with cancer who received GTX for refractory, systemic, opportunistic infections.

METHODS

Twenty recipients of high-dose donor GTX ( approximately 5.5 x 10(10) neutrophils per transfusion) who had received concurrent rIFN-gamma1b between October 2001 and December 2004 were evaluated retrospectively.

RESULTS

The median age (+/- standard deviation [SD]) was 45 +/- 17 years. Ten patients (50%) were men, 17 patients (85%) had leukemia, and 3 patients (15%) had myelodysplastic syndrome. The median +/- SD Acute Physiology and Chronic Health Evaluation II score was 15 +/- 4 (range, 7-22). Most patients (n = 18 patients; 90%) had recurrent or refractory cancer. In 6 patients (30%) who received allogeneic hematopoietic stem cell transplantation, GTX plus rIFN-gamma1b was given a median +/- SD of 26 +/- 100 days (range, 12-372 days) after transplantation. Seventeen patients (85%) had neutropenia during GTX therapy. Five patients (25%) had possible invasive fungal infection, 3 patients (15%) had probable invasive fungal infection, and 11 patients (55%) had proven invasive fungal infection. One patient (5%) had refractory Pseudomonas aeruginosa sepsis. Eight patients (40%) received corticosteroids during GTX plus rIFN-gamma1b therapy. Patients received a median +/- SD of 8 +/- 7 GTX doses (range, 4-28 doses) and 9 +/- 7 rIFN-gamma1b doses (range, 1-28 doses), for a mean +/- SD cumulative dose (CD) of 400 +/- 2621 microg. Other concomitant cytokines were granulocyte-colony stimulating factor (12 +/- 3 doses; CD, 6720 +/- 4721 microg) in 15 patients (75%) and granulocyte-macrophage-colony stimulating factor (12 +/- 9 doses; CD, 4750 +/- 4410 microg) in 14 patients (70%). Four patients (20%) developed fever, and 2 patients (10%) developed skin rashes. Reversible liver dysfunction (n = 3 patients; 15%) and tachycardia (n = 1 patients; 5%) were considered rIFN-gamma1b-associated adverse reactions; whereas, in 1 patient (5%), transient dyspnea was attributed to GTX. Four weeks after therapy started, 9 patients (45%) had complete or partial resolution of infection; and, in another 3 patients (15%), the invasive fungal infection had become stable.

CONCLUSIONS

The current results indicated that no serious adverse events were associated with rIFN-gamma1b immune enhancement in patients with systemic opportunistic infections who received donor GTX therapy.

Efficacy of a rapamycin analog (CCI-779) and IFN-gamma in tuberous sclerosis mouse models

Tuberous sclerosis complex (TSC) is a familial tumor disorder for which there is no effective medical therapy. Disease-causing mutations in the TSC1 or TSC2 gene lead to increased mammalian target of rapamycin (mTOR) kinase activity in the conserved mTOR signaling pathway, which regulates nutrient uptake, cell growth, and protein translation. The normal function of TSC1 and TSC2 gene products is to form a complex that reduces mTOR kinase activity. Thus, mTOR kinase inhibition may be a useful targeted therapeutic approach. Elevated interferon-gamma (IFN-gamma) expression is associated with decreased severity of kidney tumors in TSC patients and mouse models; therefore, IFN-gamma also has therapeutic potential. We studied cohorts of Tsc2+/- mice and a novel mouse model of Tsc2-null tumors in order to evaluate the efficacy of targeted therapy for TSC. We found that treatment with either an mTOR kinase inhibitor (CCI-779, a rapamycin analog) or with IFN-gamma reduced the severity of TSC-related disease without significant toxicity. These results constitute definitive preclinical data that justify proceeding with clinical trials using these agents in selected patients with TSC and related disorders.

Invasive aspergillosis in primary immunodeficiencies

Primary immunodeficiencies are rare and usually first manifest during childhood. Invasive aspergillosis is the leading cause of mortality in chronic granulomatous disease (CGD), reflecting the key role of the phagocyte NADPH oxidase in host defense against opportunistic fungi. Despite interferon-gamma prophylaxis, invasive filamentous fungal infections are a persistent problem in CGD. Key principles of management of fungal infections involve early recognition and aggressive treatment and appropriate surgical debridement of localized disease. Because CGD is a disorder of phagocyte stem cells in which the gene defects are well defined, it is a model disease to evaluate immune reconstitution through stem cell transplantation and gene therapy. Patients with the hyper-IgE syndrome with recurrent infections (Job syndrome) are prone to colonization of lung cavities (pneumatoceles) by Aspergillus species leading to local invasion and rarely disseminated infection. Other primary phagocytic disorders, T-cell disorders, and mitochondrial disorders are uncommonly associated with invasive aspergillosis. Taken together, these rare primary immunodeficiencies highlight the complex coordination of both innate and acquired pathways mediating host defense against Aspergillus infection.

The synergistic effect of phytohemagglutinin and interferon-gamma on the expression of tumor necrosis factor-alpha from RAW 264.7 cells

Tumor necrosis factor-alpha (TNF-alpha) is a major cytokine of host immune reaction by foreign agents. Phytohemagglutinin (PHA) is a dynamic contributor to mitogenic stimulation and augmentation of host immune defense. Interferon-gamma (IFN-gamma) induces induction of cytokines in macrophages and lymphocytes. The aim of this study was to examine the synergistic effects of PHA plus low dose IFN-gamma on TNF-alpha mRNA production, cytosolic levels, and secretion in RAW 264.7 cells. The cells were stimulated with PHA or IFN-gamma using various concentrations for various times. The effects of PHA on TNF-alpha expression appeared in dose- and time-dependent manners. The maximum doses of PHA and IFN-gamma to produce them were 300 microg/ml PHA and 10 ng/ml IFN-gamma. The optimum time of PHA for the TNF-alpha mRNA production and release were 6 and 7 h after stimulation, respectively, whereas the time of IFN-gamma on them was achieved at 3 and 8 h. Although the TNF-alpha mRNA production, cytosolic levels, and secretion from the cells were slightly detected under 10 microg/ml PHA and 1 ng/ml IFN-gamma, the combination of PHA (10 microg/ml) and IFN-gamma (1 ng/ml) greatly increased them, indicating the synergistic effect of PHA plus low dose IFN-gamma on TNF-alpha expression.

Antimicrobial reactive oxygen and nitrogen species: concepts and controversies

Phagocyte-derived reactive oxygen and nitrogen species are of crucial importance for host resistance to microbial pathogens. Decades of research have provided a detailed understanding of the regulation, generation and actions of these molecular mediators, as well as their roles in resisting infection. However, differences of opinion remain with regard to their host specificity, cell biology, sources and interactions with one another or with myeloperoxidase and granule proteases. More than a century after Metchnikoff first described phagocytosis, and more than four decades after the discovery of the burst of oxygen consumption that is associated with microbial killing, the seemingly elementary question of how phagocytes inhibit, kill and degrade microorganisms remains controversial. This review updates the reader on these concepts and the topical questions in the field.

Long-Term Interferon- Therapy for Patients with Chronic Granulomatous Disease

BACKGROUND

Chronic granulomatous disease (CGD) is a rare disorder of phagocytes in which absent production of superoxide and hydrogen peroxide in phagocytes predisposes patients to bacterial and fungal infections. Infections are dramatically reduced by prophylaxis with antibiotics, antifungals, and interferon- gamma (IFN-gamma ).

METHODS

Seventy-six patients with CGD were enrolled in an uncontrolled, open-label follow-up study to assess the long-term clinical safety and efficacy of IFN-gamma therapy. Patients received IFN-gamma subcutaneously 3 times per week.

RESULTS

We observed patients for up to 9 years, for a total observation period of 328.4 patient-years. The incidence of serious infections was 0.30 infections per patient-year; for serious bacterial infections, the incidence was 0.18 cases per patient-year, and for serious fungal infections, it was 0.12 cases per patient-year. Thirty-seven percent of patients reported an adverse event, the most common of which was fever. Twenty-six patients withdrew from the study (3 because of adverse events, 15 because of patient preference, and 8 because of transfer to another trial). There were no life-threatening IFN-gamma-related adverse events and no discernible effects on growth. The overall mortality rate was 1.5% per patient-year.

CONCLUSION

IFN-gamma prophylaxis for CGD appears to be effective and well tolerated over a prolonged period of time.

Gastrointestinal involvement in chronic granulomatous disease

OBJECTIVE

Chronic granulomatous disease (CGD) is a rare disorder of phagocyte oxidative metabolism. In addition to infectious complications, granulomatous lesions often involve hollow viscera, especially the gastrointestinal (GI) tract. The objective of this study was to evaluate the clinical presentation, prevalence, and consequences of GI involvement in patients with CGD.

METHODS

The medical records of 140 patients with CGD (67% X-linked) followed at the National Institutes of Health were reviewed and abstracted for GI manifestations. All available GI pathology was reviewed.

RESULTS

GI involvement was recorded in 46 (32.8%) of 140 patients with CGD, 89% of whom had X-linked inheritance. The median age at the time of initial GI manifestations was 5 years (range: 0.8-30 years); 70% of the affected patients presented with GI involvement in the first decade of life. Abdominal pain was the most frequent symptom (100%), and hypoalbuminemia was the most frequent sign (70%). Prednisone controlled symptoms and signs in the majority of affected patients, but relapse of symptoms occurred in 71%. GI involvement had no effect on mortality and was unassociated with interferon-gamma use.

CONCLUSION

GI involvement is a common and recurring problem in CGD, especially in those with X-linked inheritance. Currently, there is no clear evidence for an infectious cause. The frequency of GI involvement is unaffected by the use of interferon-gamma and does not affect mortality. GI involvement should be sought in patients who have CGD with abdominal pain, growth delay, or hypoalbuminemia.

Phagocyte NADPH oxidase, but not inducible nitric oxide synthase, is essential for early control of Burkholderia cepacia and chromobacterium violaceum infection in mice

Reactive oxygen and nitrogen intermediates have critical, partially overlapping roles in host defense against a variety of pathogens. Using mice deficient in generating phagocyte superoxide (p47(phox)(-/-)) and mice deficient in generating inducible nitric oxide synthase (iNOS(-/-)), we examined the roles of these reactive species in host defense against Burkholderia cepacia and Chromobacterium violaceum, organisms known to have unusual virulence in chronic granulomatous disease. Intraperitoneal B. cepacia challenge (4.0 x 10(3) to 4.0 x 10(5) organisms/mouse) resulted in mortality in all p47(phox)(-/-) mice, with the survival interval being inversely proportionate to the amount of inoculum. Pretreatment with gamma interferon did not affect survival. C. violaceum was strikingly virulent in p47(phox)(-/-) mice (the 50% lethal dose [LD(50)] was <13 organisms). iNOS(-/-) and wild-type mice were resistant to B. cepacia challenges of at least 10(6) organisms per mouse, and the LD(50) of C. violaceum was between 10(6) and 10(7) organisms per mouse. Consistent with the survival data, numbers of organisms in cultures of B. cepacia from multiple sites were higher for p47(phox)(-/-) mice than for iNOS(-/-) and wild-type mice at day 4 after challenge, but numbers of organisms for different B. cepacia strains varied. The recovery of C. violaceum was strikingly greater at 18 h after challenge for p47(phox)(-/-) mice than for iNOS(-/-) and wild-type mice, in which the organism burdens were virtually nil. In vitro, both B. cepacia and C. violaceum were sensitive to H(2)O(2) and to reactive nitrogen intermediates but the sensitivities of different strains varied significantly. Host defense against B. cepacia and C. violaceum is critically dependent in vivo on reactive oxygen intermediates, and these species are model organisms to further dissect host and pathogen interactions related to the generation and scavenging of microbicidal reactive intermediates.

Nocardia infection in chronic granulomatous disease

To determine the clinical characteristics and outcome of Nocardia infection in patients with chronic granulomatous disease (CGD), we reviewed data on 28 episodes of Nocardia infection in 23 patients with CGD. All episodes involved pulmonary infection. The frequency of disseminated nocardiosis was 25% for the case series overall, but it was 56% among episodes in patients receiving neither interferon-gamma (IFN-gamma) nor sulfonamide prophylaxis. Patients receiving prophylaxis with IFN-gamma and/or a sulfonamide were significantly less likely to have disseminated nocardiosis than were patients not receiving these medications, and no patient receiving both medications developed disseminated nocardiosis. One-third of the patients had concomitant fungal infections, and 2 patients had concomitant Legionella infections. The majority of patients were successfully treated with a sulfonamide-containing regimen, even though some patients had developed Nocardia infection while receiving sulfonamide prophylaxis. Nocardia infections in patients with CGD are not usually fatal if treated properly, and prophylaxis with IFN-gamma and a sulfonamide may protect against dissemination.