Primary phagocytic disorders of childhood

Functional Characterization of Clinical Isolates of the Opportunistic Fungal Pathogen Aspergillus nidulans

Aspergillus nidulans is an opportunistic fungal pathogen in patients with immunodeficiency, and virulence of A. nidulans isolates has mainly been studied in the context of chronic granulomatous disease (CGD), with characterization of clinical isolates obtained from non-CGD patients remaining elusive. This study therefore carried out a detailed biological characterization of two A. nidulans clinical isolates (CIs), obtained from a patient with breast carcinoma and pneumonia and from a patient with cystic fibrosis that underwent lung transplantation, and compared them to the reference, nonclinical FGSC A4 strain. Both CIs presented increased growth in comparison to that of the reference strain in the presence of physiologically relevant carbon sources. Metabolomic analyses showed that the three strains are metabolically very different from each other in these carbon sources. Furthermore, the CIs were highly susceptible to cell wall-perturbing agents but not to other physiologically relevant stresses. Genome analyses identified several frameshift variants in genes encoding cell wall integrity (CWI) signaling components. Significant differences in CWI signaling were confirmed by Western blotting among the three strains. In vivo virulence studies using several different models revealed that strain MO80069 had significantly higher virulence in hosts with impaired neutrophil function than the other strains. In summary, this study presents detailed biological characterization of two A. nidulanssensu stricto clinical isolates. Just as in Aspergillus fumigatus, strain heterogeneity exists in A. nidulans clinical strains that can define virulence traits. Further studies are required to fully characterize A. nidulans strain-specific virulence traits and pathogenicity.IMPORTANCE Immunocompromised patients are susceptible to infections with opportunistic filamentous fungi from the genus Aspergillus Although A. fumigatus is the main etiological agent of Aspergillus species-related infections, other species, such as A. nidulans, are prevalent in a condition-specific manner. A. nidulans is a predominant infective agent in patients suffering from chronic granulomatous disease (CGD). A. nidulans isolates have mainly been studied in the context of CGD although infection with A. nidulans also occurs in non-CGD patients. This study carried out a detailed biological characterization of two non-CGD A. nidulans clinical isolates and compared the results to those with a reference strain. Phenotypic, metabolomic, and genomic analyses highlight fundamental differences in carbon source utilization, stress responses, and maintenance of cell wall integrity among the strains. One clinical strain had increased virulence in models with impaired neutrophil function. Just as in A. fumigatus, strain heterogeneity exists in A. nidulans clinical strains that can define virulence traits.

Efficacy of Olorofim (F901318) against Aspergillus fumigatus, A. nidulans, and A. tanneri in Murine Models of Profound Neutropenia and Chronic Granulomatous Disease

The emergence of azole resistance in Aspergillus fumigatus as well as an increasing frequency of multiresistant cryptic Aspergillus spp. necessitates exploration of new classes of antifungals. Olorofim (formerly F901318) is a new fungicidal agent that prevents the growth of ascomycetous mold species via inhibition of de novo pyrimidine biosynthesis, a mechanism of action distinct from that of currently available antifungal drugs. We studied the in vivo efficacy of olorofim intraperitoneal therapy (15 mg/kg of body weight every 8 h for 9 days) against infection with A. fumigatus, A. nidulans, and A. tanneri in both neutropenic CD-1 mice and mice with chronic granulomatous disease (CGD) (gp91 ^-/- phox mice). In the neutropenic mouse model, 80% to 88% of treated mice survived for 10 days, and in the CGD group, 63% to 88% of treated mice survived for 10 days, depending on the infecting species, while less than 10% of the mice in the control groups survived for 10 days. In the olorofim-treated groups, galactomannan levels were significantly suppressed, with lower organ fungal DNA burdens being seen for all three Aspergillus spp. Histopathological slides revealed a limited number of inflammatory foci with or without detectable fungal elements in the kidneys of neutropenic CD-1 mice and in the lungs of CGD mice. Furthermore, the efficacy of olorofim was unrelated to the triazole MICs of the infecting Aspergillus spp. These results show olorofim to be a promising therapeutic agent for invasive aspergillosis.

Emerging Aspergillus Species Almost Exclusively Associated With Primary Immunodeficiencies

Invasive aspergillosis (IA) is the most serious mold infection encountered in patients with iatrogenic immunosuppression. IA is also a major cause of mortality and morbidity in individuals with primary immunodeficiency (PID). Although Aspergillus fumigatus is the most common etiologic agent of IA reported in PID patients, followed by A. nidulans, multiple poorly recognized Aspergillus species such as A. udagawae, A. quadrilineatus, A. pseudoviridinutans, A. tanneri, A. subramanianii, and A. fumisynnematus have been reported almost exclusively from patients with inborn defects in host antifungal defense pathways. Infection in PID patients exhibits patterns of disease progression distinct from those in iatrogenic immunosuppression. Specifically, the disease can be extrapulmonary and chronic with a tendency to disseminate in a contiguous manner across anatomical planes. It is also more refractory to standard antifungal therapy. This synopsis summarizes our understanding of emerging rare Aspergillus species that primarily affect patients with PIDs but not those with acquired immunodeficiencies.

Exogenous Stimulation of Type I Interferon Protects Mice with Chronic Granulomatous Disease from Aspergillosis through Early Recruitment of Host-Protective Neutrophils into the Lung

Invasive aspergillosis (IA) remains the primary cause of morbidity and mortality in chronic granulomatous disease (CGD) patients, often due to infection by Aspergillus species refractory to antifungals. This motivates the search for alternative treatments, including immunotherapy. We investigated the effect of exogenous type I interferon (IFN) activation on the outcome of IA caused by three Aspergillus species, A. fumigatus, A. nidulans, and A. tanneri, in CGD mice. The animals were treated with poly(I):poly(C) carboxymethyl cellulose poly-l-lysine (PICLC), a mimetic of double-stranded RNA, 24 h preinfection and postinfection. The survival rates and lung fungal burdens were markedly improved by PICLC immunotherapy in animals infected with any one of the three Aspergillus species. While protection from IA was remarkable, PICLC induction of type I IFN in the lungs surged 24 h posttreatment and returned to baseline levels by 48 h, suggesting that PICLC altered early events in protection against IA. Immunophenotyping of recruited leukocytes and histopathological examination of tissue sections showed that PICLC induced similar cellular infiltrates as those in untreated-infected mice, in both cases dominated by monocytic cells and neutrophils. However, the PICLC immunotherapy resulted in a marked earlier recruitment of the leukocytes. Unlike with conidia, infection with A. nidulans germlings reduced the protective effect of PICLC immunotherapy. Additionally, antibody depletion of neutrophils totally reversed the protection, suggesting that neutrophils are crucial for PICLC-mediated protection. Together, these data show that prophylactic PICLC immunotherapy prerecruits these cells, enabling them to attack the conidia and thus resulting in a profound protection from IA.IMPORTANCE Patients with chronic granulomatous disease (CGD) are highly susceptible to invasive aspergillosis (IA). While Aspergillus fumigatus is the most-studied Aspergillus species, CGD patients often suffer IA caused by A. nidulans, A. tanneri, and other rare species. These non-fumigatus Aspergillus species are more resistant to antifungal drugs and cause higher fatality rates than A. fumigatus Therefore, alternative therapies are needed to protect CGD patients. We report an effective immunotherapy of mice infected with three Aspergillus species via PICLC dosing. While protection from IA was long lasting, PICLC induction of type I IFN surged but quickly returned to baseline levels, suggesting that PICLC was altering early events in IA. Interestingly, we found responding immune cells to be similar between PICLC-treated and untreated-infected mice. However, PICLC immunotherapy resulted in an earlier recruitment of the leukocytes and suppressed fungal growth. This study highlights the value of type I IFN induction in CGD patients.

[Sarcoidosis in childhood. A rare systemic disease]

BACKGROUND

Sarcoidosis is a systemic disease of unknown etiology that rarely occurs in children. It usually affects the lungs, however, it may involve various organs. It occasionally affects the general condition, and causes fever, hepatomegaly and splenomegaly.

CASE REPORT

We report the case of a twelve-year-old adolescent with late-onset childhood sarcoidosis which diagnosis was confirmed by lymph node histopathological study. The patient presented general condition, hypercalcemia, erythema nodosum, severe lung disorders, lymphadenopathy, hepatomegaly and testicular mass. He received treatment with steroids, with excellent clinical response.

CONCLUSIONS

We highlight the importance of considering the diagnosis of sarcoidosis in patients with hepatomegaly, lymphadenopathy, diffuse lung damage, erythema nodosum, testicular mass and hypercalcemia, as well as the need for a multidisciplinary approach to assess multiple organ involvement and the early beginning of steroid treatment in order to prevent the progression of the disease.

Enhancement of neutrophil autophagy by an IVIG preparation against multidrug-resistant bacteria as well as drug-sensitive strains

Autophagy occurs in human neutrophils after the phagocytosis of multidrug-resistant bacteria and drug-sensitive strains, including Escherichia coli and Pseudomonas aeruginosa. The present study detected autophagy by immunoblot analysis of LC3B conversion, by confocal scanning microscopic examination of LC3B aggregate formation and by transmission electron microscopic examination of bacteria-containing autophagosomes. Patients with severe bacterial infections are often treated with IVIG alongside antimicrobial agents. Here, we showed that IVIG induced neutrophil-mediated phagocytosis of multidrug-resistant strains. Compared with untreated neutrophils, neutrophils exposed to IVIG showed increased levels of bacterial cell killing, phagocytosis, O(2)(-) release, MPO release, and NET formation. IVIG also increased autophagy in these cells. Inhibiting the late phase of autophagy (fusion of lysosomes with autophagosomes) with bafilomycin A1-reduced, neutrophil-mediated bactericidal activity. These findings indicate that autophagy plays a critical role in the bactericidal activity mediated by human neutrophils. Furthermore, the autophagosomes within the neutrophils contained bacteria only and their organelles only, or both bacteria and their organelles, a previously undocumented observation. Taken together, these results suggest that the contents of neutrophil autophagosomes may be derived from specific autophagic systems, which provide the neutrophil with an advantage. Thus, IVIG promotes the neutrophil-mediated killing of multidrug-resistant bacteria as well as drug-sensitive strains.

Renal transplantation in a patient with chronic granulomatous disease: case report

Chronic granulomatous disease (CGD) is a genetic disease caused by structural mutations in the enzyme NADPH oxidase that results in severe immunodeficiency. End-stage renal disease occurs in this patient population and is attributed to various factors, including infections, amyloidosis, and nephrotoxic anti-infective agents. In this report, we present our experience in transplantation for a patient with CGD complicated by isolated hepatic tuberculosis abscess. The course of the case demonstrates the absolute requirements for a multidisciplinary and compulsive approach before, during, and after transplantation. This case report also highlights the unexpectedly benign effects of immunosuppressive therapy in this patient population.

[Anesthetic considerations in primary immunodeficiencies]

Primary immunodeficiencies are a group of mostly hereditary, or congenital, disorders. Some cases, however, show no hereditary pattern despite an evident familial distribution. The incidence of these cases is variable and the most frequent of them is immunoglobulin A deficiency. Many are pediatric disorders that are occasionally so serious that the patient does not survive the first year of life due to the development of systemic infections. In other cases, survival is much longer and it is possible to find adult carriers in routine clinical practice. These are less aggressive cases that form part of specific clinical syndromes that must be recognized so that appropriate anesthetic management can be planned. We review the clinical characteristics of primary immunodeficiencies that may be relevant to anesthetic management in these patients.

Diversion of the fecal stream resolves ulcerative colitis complicating chronic granulomatous disease in an adult patient

Chronic granulomatous disease (CGD) is a primary phagocytic disorder characterized by greatly increased susceptibility to severe bacterial and fungal infections. Patients with CGD may have gastrointestinal manifestations, commonly colitis, usually mimicking Crohn disease. We report an adult case, the second in literature, of CGD with severe colitis displaying histologic features of ulcerative colitis. The patient had a prompt improvement (continuing up to more than 5 y of follow-up) of the clinical picture after ileostomy and fecal diversion.

Effect of amphotericin B and micafungin combination on survival, histopathology, and fungal burden in experimental aspergillosis in the p47phox-/- mouse model of chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited disorder of the NADPH oxidase characterized by recurrent life-threatening bacterial and fungal infections. We characterized the effects of single and combination antifungal therapy on survival, histopathology, and laboratory markers of fungal burden in experimental aspergillosis in the p47phox-/- knockout mouse model of CGD. CGD mice were highly susceptible to intratracheal Aspergillus fumigatus challenge, whereas wild-type mice were resistant. CGD mice were challenged intratracheally with a lethal inoculum (1.25 x 10(4) CFU/mouse) of A. fumigatus and received one of the following regimens daily from day 0 to 4 after challenge (n = 19 to 20 per treatment group): (i) vehicle, (ii) amphotericin B (intraperitoneal; 1 mg/kg of body weight), (iii) micafungin (intravenous; 10 mg/kg), or (iv) amphotericin B plus micafungin. The rank order of therapeutic efficacy based on prolonged survival, from highest to lowest, was as follows: amphotericin B plus micafungin, amphotericin B alone, micafungin alone, and the vehicle. Lung histology showed pyogranulomatous lesions and invasive hyphae, but without hyphal angioinvasion or coagulative necrosis. Treatment with micafungin alone or combined with amphotericin B produced swelling of invasive hyphae that was not present in mice treated with the vehicle or amphotericin B alone. Assessment of lung fungal burden by quantitative PCR showed no significant difference between treatment groups. Serum galactomannan levels were at background despite documentation of invasive aspergillosis by histology. Our findings showed the superior efficacy of the amphotericin B and micafungin combination compared to either agent alone after A. fumigatus challenge and also demonstrated unique features of CGD mice as a model for experimental aspergillosis.

Successful renal transplantation in patients with chronic granulomatous disease

Chronic granulomatous disease (CGD) is a genetic disease caused by structural mutations in the enzyme NADPH oxidase that results in severe immunodeficiency. End-stage renal disease occurs in this patient population, and is often attributed to the necessary use of nephrotoxic anti-infectives. In this report, we present the experiences of two centers in transplantation of three patients with CGD: one transplanted with CGD, one cured of his CGD with bone marrow transplantation who subsequently underwent kidney transplantation and one that received a kidney transplant prior to being cured of CGD via a sequential peripheral blood stem cell transplant (SCT). All three recipients have enjoyed excellent outcomes. Their courses demonstrate the absolute requirements for a multidisciplinary and compulsive approach before, during and after transplantation. These case reports also highlight the unexpectedly benign effects of immunosuppressive therapy in this patient population.

Increased chemoattractant induced neutrophil oxidative burst, accelerated apoptosis, and dysregulated tyrosine phosphorylation associated with lifelong bacterial infections

A boy with lifelong recurrent bacterial infection at cutaneous and mucosal sites was investigated. PMN oxidative burst to phorbol myristate acetate (PMA) and zymosan was normal but was increased 20- to 50-fold upon C5a or formyl-met-leu-phe (fMLP) chemoattractant stimulation, accompanied by accelerated PMN apoptosis. His PMNs showed increased constitutive tyrosine phosphorylation of 21-, 25-, and 44-kDa proteins, and of src-family kinases (p59(hck), p58(fgr), and p53/56(lyn)). Phosphorylation was abnormally enhanced following fMLP stimulation. Expression and activity of the major PMN tyrosine phosphatases, i.e., CD45, CD148, and SHP-1 and -2, was normal. However, dephosphorylation of phospho-p58(fgr) and phospho-p53/56(lyn) by lysates of patient's PMNs was enhanced. Thus, another phosphatase may be overactive, perhaps dephosphorylating a regulatory (inhibitory) site on a protein tyrosine kinase, accounting for the abnormal PMN tyrosine phosphorylation and function. With age (now 13 years), T-cell lymphopenia and loss of T-cell responses developed. This appears to be a unique primary immunodeficiency with abnormal PMN oxidative and apoptotic responses to chemoattractants, dysregulated protein tyrosine phosphorylation, serious bacterial infection, and T-lymphocyte attrition.

Kostmann's syndrome

Kostmann's syndrome is a rare congenital disorder of neutrophil production due to impairment of myeloid differentiation in the bone marrow, with the neutrophil count being characteristically less than 500 x 10(3) cells/l (normal: 2-7 x 10(9)/l). Severe persistent neutropenia results in an increased susceptibility to frequent bacterial infections. The condition can be treated with recombinant human granulocyte colony-stimulating factor (G-CSF). Although several articles have addressed the clinicopathological and haematological aspects of this disorder, little or no information has been available concerning the radiological findings in this disorder. This report summarizes the clinical features, radiological findings and management of a patient with Kostmann's syndrome.

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.

Urokinase-deficient and urokinase receptor-deficient mice have impaired neutrophil antimicrobial activation in vitro

Leukocytes express both urokinase-type plasminogen activator (uPA) and the urokinase receptor (uPAR, CD87). We have shown that neutrophil recruitment to the lung during P. aeruginosa pneumonia is impaired in uPAR-deficient (uPAR-/-) mice but is normal in uPA-/- mice. However, both uPA-/- mice and uPAR-/- mice have impaired lung clearance of P. aeruginosa compared with wild-type (WT) mice. To determine the role of uPA and uPAR in antibacterial host defense, we compared neutrophil bacterial-phagocytosis, respiratory burst, and degranulation among uPA-/-, uPAR-/-, and WT mice. Neutrophil phagocytosis was significantly diminished comparing uPA-/- and uPAR-/- mice with WT mice at all time points. The generation of superoxide by both uPA-/- and uPAR-/- neutrophils was about half of that seen in WT neutrophils. Degranulation of azurophilic granules was significantly diminished in uPA-/- neutrophils compared with either uPAR-/- or WT neutrophils. By contrast, agonist-stimulated release of specific granules was not diminished in either uPA-/- or uPAR-/- mice compared with WT. We conclude that the uPA/uPAR system modulates several of the crucial steps in neutrophil activation that result in bacterial killing and effective innate host defense.

A 5-week-old HIV-1–exposed girl with failure to thrive and diffuse nodular pulmonary infiltrates

A 5-week-old female infant with vertical HIV-1 exposure, progressive cough, and failure to thrive was given a diagnosis of bilateral diffuse nodular lung lesions. The child was without fever, leukocytosis, anemia, peripheral adenopathy, or hepatosplenomegaly, and the results of repeated blood tests for HIV-1 DNA were negative. A needle biopsy of the lungs revealed granulomatous inflammation and giant cells, with fungal organisms suggestive of Aspergillus species. A nitroblue tetrazolium dye test performed on the patient's blood specimen demonstrated absence of dye reduction, suggesting a diagnosis of chronic granulomatous disease. Further analysis revealed that the child had a deficiency of the p47(phox) component of the nicotinamide adenine dinucleotide phosphate oxidase system. Thus this child with vertical HIV-1 exposure and diffuse pulmonary nodules actually had an autosomal recessive form of chronic granulomatous disease. This case study clearly demonstrates that children with suspected HIV-1 infection might also need evaluation for primary immunodeficiency and that the clinical immunology laboratory is a powerful adjunct in coming to a correct diagnosis.

How to leverage an endogenous immune defense mechanism: the example of granulocyte colony-stimulating factor

Our understanding of host defense has exploded during the past two decades. It is temping to take advantage of this knowledge by considering the modulation and control of these mechanisms as therapeutic options. In intensive care medicine, the aim is usually to block an overwhelming inflammatory response, which represents the "bad" side of the double-edged sword of host defense. The obvious danger of such treatment strategies is that impairing the inflammatory reaction means impairing host defense in patients exposed to infectious agents. The alternative approach, i.e., strengthening or supplementing favorable host defense mechanism, has so far been little explored clinically. Granulocyte colony-stimulating factor, the granulocyte colony-stimulating factor, combines the unique properties of an anti-infectious and an anti-inflammatory factor. This attractive profile has led us to various approaches to exploit these immunomodulatory activities. In a recently terminated, placebo-controlled, randomized study, we investigated if prophylactic treatment with rh granulocyte colony-stimulating factor (Filgrastim), at the time a risk can be anticipated such as before an operation, may offer protection from immunoinflammatory dyshomeostasis and thus lower the incidence of postoperative sepsis. Perioperative rh granulocyte colony-stimulating factor administration, compared with placebo treatment, resulted in the prevention of postoperative monocyte deactivation, conservation of an adequate Th1/Th2 ratio, as well as a considerable alleviation of the acute phase response. In parallel, there was a clear tendency toward lowering the rate of postoperative septic complications under the administration of Filgrastim.

Ecthyma gangrenosum: considerations in a previously healthy child

Ecthymagangrenosum is a skin lesion that is most commonly caused by. Although ecthyma gangrenosum usually develops in patients with underlying immunodeficiencies or chronic diseases, there have been reports of its appearance in previously healthy children. A review of such patients in the English literature showed that most of them had either previously undetected immunodeficiencies or transient risk factors that predisposed them to the development of ecthyma gangrenosum. We report a patient without apparent antecedent predisposing risk factors for ecthyma gangrenosum who developed chronic neutropenia 1 week after presentation. It is important for the primary care provider to recognize ecthyma gangrenosum, treat it with appropriate antimicrobial agents and investigate the patient for occult immunodeficiencies.

Assessment of the child with recurrent chest infections

The child with recurrent chest infections presents the clinician with a difficult diagnostic challenge. Does the child have a simply-managed cause for their symptoms, such as recurrent viral respiratory infections or asthma, or is there evidence of a more serious underlying pathology, such as bronchiectasis? Many different disorders present in this way, including cystic fibrosis, a range of immunodeficiency syndromes, and congenital abnormalities of the respiratory tract. In some affected children, lung damage follows a single severe pneumonia: in others it is the result of inhalation of food or a foreign body. The assessment of these children is demanding: it requires close attention to the history and examination, and in selected cases, extensive investigations. Early and accurate diagnosis is essential to ensure that optimal treatment is given and to minimise the risk of progressive or irreversible lung damage. The aim of this chapter is to examine the causes of recurrent chest infections and to describe how this complex group of children should be assessed and investigated.

The immunologic workup of the child suspected of immunodeficiency

OBJECTIVE

This review is intended to provide an outline for the evaluation of patients suspected of having immunodeficiency, a problem that is frequently encountered in clinical practice.

DATA SOURCES

Information was obtained through a MEDLINE literature search as well as from standard textbooks in immunology. Also included is information that reflects the authors' clinical experience in the field.

RESULTS

In general clinical practice, many physicians feel inadequate to evaluate patients with suspected immune deficiencies. They also think that the process of evaluation is time-consuming, which results in misdiagnosis of a substantial percentage of such disorders. Hence, the prevalence of immunodeficiency disorders is much higher than generally thought. At present, there are >80 unique primary immunodeficiency conditions and >50 syndromes that are associated with various immunologic defects. The prevalence of secondary immunodeficiency has also been increasing because of the tragic epidemic of HIV infection, more usage of immunosuppressive medications and bone marrow stem cell transplantation, and the severe degree of malnutrition in underdeveloped countries. It is necessary for clinicians, particularly the specialists in allergy and immunology, to be able to evaluate the status of the immune system.

CONCLUSIONS

Very valuable information can be gathered from the medical history and physical examination that may exclude or increase the suspicion of immunologic defect. Laboratory tests can then be appropriately selected to define the specific defect. Once the diagnosis has been settled, proper medical management can be instituted with subsequent improvement in morbidity and mortality of such disorders.