Hematologically important mutations: Leukocyte adhesion deficiency (second update)

Leukocyte adhesion deficiency (LAD) is an immunodeficiency caused by defects in the adhesion of leukocytes (especially neutrophils) to the blood vessel wall. As a result, patients with LAD suffer from severe bacterial infections and impaired wound healing, accompanied by neutrophilia. In LAD-I, characterized directly after birth by delayed separation of the umbilical cord, mutations are found in ITGB2, the gene that encodes the β subunit (CD18) of the β₂ integrins. In the rare LAD-II disease, the fucosylation of selectin ligands is disturbed, caused by mutations in SLC35C1, the gene that encodes a GDP-fucose transporter of the Golgi system. LAD-II patients lack the H and Lewis Le^a and Le^b blood group antigens. Finally, in LAD-III, the conformational activation of the hematopoietically expressed β integrins is disturbed, leading to leukocyte and platelet dysfunction. This last syndrome is caused by mutations in FERMT3, encoding the kindlin-3 protein in all blood cells, involved in the regulation of β integrin conformation. This article contains an update of the mutations that we consider to be relevant for the various forms of LAD.

A Novel Deletion in FERMT3 Causes LAD-III in a Turkish Family

Leukocyte adhesion deficiency-III (LAD-III) is an extremely rare autosomal recessive syndrome caused by mutations in FERMT3, the gene encoding kindlin-3. The genetic alterations in this gene lead to abnormal expression or activity of kindlin-3 in leukocytes and platelets. Kindlin-3 acts as an important regulator of integrin activation. LAD-III has features of the bleeding syndrome of Glanzmann and also of leukocyte adhesion deficiency. In this study, we report on two families, one of Turkish and one of Syrian origin, with clinical features of LAD-III, loss of kindlin-3 protein expression, and a functional leukocyte defect. A novel, homozygous deletion in FERMT3 (c.921delC, p.Ser307Argfs*21) was found in the Turkish patient. The parents were carriers of the mutation, consistent with an autosomal recessive inheritance. A common c.1525C > T (p.Arg509*) mutation was found in the Syrian patient. In conclusion, beside the variant c.1525C > T in the FERMT3 gene, which was previously found in more than 15 patients in Anatolia, our study is the first to identify the novel homozygous variant c.921delC in the FERMT3 gene.

Hematologically important mutations: The autosomal forms of chronic granulomatous disease (third update)

Chronic granulomatous disease (CGD) is an immunodeficiency disorder affecting about 1 in 250,000 individuals. CGD patients suffer from severe, recurrent bacterial and fungal infections. The disease is caused by mutations in the genes encoding the components of the leukocyte NADPH oxidase. This enzyme produces superoxide, which is subsequently metabolized to hydrogen peroxide and other reactive oxygen species (ROS). These products are essential for intracellular killing of pathogens by phagocytic leukocytes (neutrophils, eosinophils, monocytes and macrophages). The leukocyte NADPH oxidase is composed of five subunits, four of which are encoded by autosomal genes. These are CYBA, encoding p22^phox, NCF1, encoding p47^phox, NCF2, encoding p67^phox and NCF4, encoding p40^phox. This article lists all mutations identified in these genes in CGD patients. In addition, cytochrome b₅₅₈ chaperone-1 (CYBC1), recently recognized as an essential chaperone protein for the expression of the X-linked NADPH oxidase component gp91^phox (also called Nox2), is encoded by the autosomal gene CYBC1. Mutations in this gene also lead to CGD. Finally, RAC2, a small GTPase of the Rho family, is needed for activation of the NADPH oxidase, and mutations in the RAC2 gene therefore also induce CGD-like symptoms. Mutations in these last two genes are also listed in this article.

Clinical and laboratory findings in patients with leukocyte adhesion deficiency type I: A multicenter study in Turkey

Leukocyte adhesion deficiency type I is a rare primary immunodeficiency disorder characterized by mutations in the ITGB2 gene encoding CD18. We present clinical and immunological features of 15 patients with leukocyte adhesion deficiency type 1 (LAD-1). Targeted next-generation sequencing was performed with either a primary immunodeficiency gene panel comprising 266 genes or a small LAD-panel consisting of five genes for genetic analysis. To measure the expression level of integrins on the leukocyte surface, flow cytometry analysis was performed. The median age of the patients at diagnosis was 3 (1-48) months. Eleven (73%) of the 15 patients had a LAD-1 diagnosis in their first 6 months and 14 (93%) patients had consanguineous parents. Delayed separation of the umbilical cord was present in 80% (n = 12) of the patients in our cohort, whereas omphalitis was observed in 53% (n = 8) of the patients. Leukocytosis with neutrophil predominance was observed in 73% (n = 11) patients. Nine distinct variants in the ITGB2 gene in 13 of the 15 patients with LAD-1 were characterized, two of which (c.305_306delAA and c.779_786dup) are novel homozygous mutations of ITGB2. Four unrelated patients from Syria had a novel c.305_306delAA mutation that might be a founder effect for patients of Syrian origin. Four (27%) patients underwent hematopoietic stem cell transplantation. Two patients died because of HSCT complications and the other two are alive and well. Early differential diagnosis of the patients is critical in the management of the disease and genetic evaluation provides a basis for family studies and genetic counseling.

Mutations in cis that affect mRNA synthesis, processing and translation

Genetic mutations that cause hereditary diseases usually affect the composition of the transcribed mRNA and its encoded protein, leading to instability of the mRNA and/or the protein. Sometimes, however, such mutations affect the synthesis, the processing or the translation of the mRNA, with similar disastrous effects. We here present an overview of mRNA synthesis, its posttranscriptional modification and its translation into protein. We then indicate which elements in these processes are known to be affected by pathogenic mutations, but we restrict our review to mutations in cis, in the DNA of the gene that encodes the affected protein. These mutations can be in enhancer or promoter regions of the gene, which act as binding sites for transcription factors involved in pre-mRNA synthesis. We also describe mutations in polyadenylation sequences and in splice site regions, exonic and intronic, involved in intron removal. Finally, we include mutations in the Kozak sequence in mRNA, which is involved in protein synthesis. We provide examples of genetic diseases caused by mutations in these DNA regions and refer to databases to help identify these regions. The over-all knowledge of mRNA synthesis, processing and translation is essential for improvement of the diagnosis of patients with genetic diseases.

Clinical and Immunological Characteristics of 63 Patients with Chronic Granulomatous Disease: Hacettepe Experience

BACKGROUND

Chronic granulomatous disease (CGD), one of the phagocytic system defects, is the primary immunodeficiency caused by dysfunction of the NADPH oxidase complex which generates reactive oxygen species (ROS), which are essential for killing pathogenic microorganisms, especially catalase-positive bacteria and fungi.

OBJECTIVE

The objective of our study was to assess the clinical and laboratory characteristics, treatment modalities, and prognosis of patients with CGD.

METHODS

We retrospectively reviewed 63 patients with CGD who have been diagnosed, treated, and/or followed-up between 1984 and 2018 in Hacettepe University, Ankara, in Turkey, as a developing country.

RESULTS

The number of female and male patients was 26/37. The median age at diagnosis was 3.8 (IQR: 1.0-9.6) years. The rate of consanguinity was 63.5%. The most common physical examination finding was lymphadenopathy (44/63), growth retardation (33/63), and hepatomegaly (27/63). One adult patient had squamous cell carcinoma of the lung. The most common infections were lung infection (53/63), skin abscess (43/63), and lymphadenitis (19/63). Of the 63 patients with CGD, 6 patients had inflammatory bowel disease (IBD). Twelve of the 63 patients died during follow-up. CYBA, NCF1, CYBB, and NCF2 mutations were detected in 35%, 27.5%, 25%, and 12.5% of the patients, respectively.

CONCLUSION

We identified 63 patients with CGD from a single center in Turkey. Unlike other cohort studies in Turkey, due to the high consanguineous marriage rate in our study group, AR form of CGD was more frequent, and gastrointestinal involvement were found at relatively lower rates. The rate of patients who treated with HSCT was lower in our research than in the literature. A majority of the patients in this study received conventional prophylactic therapies, which highlight on the outcome of individuals who have not undergone HSCT.

Membrane Dynamics and Organization of the Phagocyte NADPH Oxidase in PLB-985 Cells

Neutrophils are the first cells recruited at the site of infections, where they phagocytose the pathogens. Inside the phagosome, pathogens are killed by proteolytic enzymes that are delivered to the phagosome following granule fusion, and by reactive oxygen species (ROS) produced by the NADPH oxidase. The NADPH oxidase complex comprises membrane proteins (NOX2 and p22^phox), cytoplasmic subunits (p67^phox, p47^phox, and p40^phox) and the small GTPase Rac. These subunits assemble at the phagosomal membrane upon phagocytosis. In resting neutrophils the catalytic subunit NOX2 is mainly present at the plasma membrane and in the specific granules. We show here that NOX2 is also present in early and recycling endosomes in human neutrophils and in the neutrophil-like cell line PLB-985 expressing GFP-NOX2. In the latter cells, an increase in NOX2 at the phagosomal membrane was detected by live-imaging after phagosome closure, probably due to fusion of endosomes with the phagosome. Using super-resolution microscopy in PLB-985 WT cells, we observed that NOX2 forms discrete clusters in the plasma membrane. The number of clusters increased during frustrated phagocytosis. In PLB-985NCF1ΔGT cells that lack p47^phox and do not assemble a functional NADPH oxidase, the number of clusters remained stable during phagocytosis. Our data suggest a role for p47^phox and possibly ROS production in NOX2 recruitment at the phagosome.

Microscopic resection margin status in pancreatic ductal adenocarcinoma - A nationwide analysis

INTRODUCTION

First, this study aimed to assess the prognostic value of different definitions for resection margin status on disease-free survival (DFS) and overall survival (OS) in pancreatic ductal adenocarcinoma (PDAC). Second, preoperative predictors of direct margin involvement were identified.

MATERIALS AND METHODS

This nationwide observational cohort study included all patients who underwent upfront PDAC resection (2014-2016), as registered in the prospective Dutch Pancreatic Cancer Audit. Patients were subdivided into three groups: R0 (≥1 mm margin clearance), R1 (<1 mm margin clearance) or R1 (direct margin involvement). Survival was compared using multivariable Cox regression analysis. Logistic regression with baseline variables was performed to identify preoperative predictors of R1 (direct).

RESULTS

595 patients with a median OS of 18 months (IQR 10-32 months) months were analysed. R0 (≥1 mm) was achieved in 277 patients (47%), R1 (<1 mm) in 146 patients (24%) and R1 (direct) in 172 patients (29%). R1 (direct) was associated with a worse OS, as compared with both R0 (≥1 mm) (hazard ratio (HR) 1.35 [95% and confidence interval (CI) 1.08-1.70); P < 0.01) and R1 (<1 mm) (HR 1.29 [95%CI 1.01-1.67]; P < 0.05). No OS difference was found between R0 (≥1 mm) and R1 (<1 mm) (HR 1.05 [95% CI 0.82-1.34]; P = 0.71). Preoperative predictors associated with an increased risk of R1 (direct) included age, male sex, performance score 2-4, and venous or arterial tumour involvement.

CONCLUSION

Resection margin clearance of <1 mm, but without direct margin involvement, does not affect survival, as compared with a margin clearance of ≥1 mm. Given that any vascular tumour involvement on preoperative imaging was associated with an increased risk of R1 (direct) resection with upfront surgery, neoadjuvant therapy might be considered in these patients.

Neutrophils Kill Antibody-Opsonized Cancer Cells by Trogoptosis

Destruction of cancer cells by therapeutic antibodies occurs, at least in part, through antibody-dependent cellular cytotoxicity (ADCC), and this can be mediated by various Fc-receptor-expressing immune cells, including neutrophils. However, the mechanism(s) by which neutrophils kill antibody-opsonized cancer cells has not been established. Here, we demonstrate that neutrophils can exert a mode of destruction of cancer cells, which involves antibody-mediated trogocytosis by neutrophils. Intimately associated with this is an active mechanical disruption of the cancer cell plasma membrane, leading to a lytic (i.e., necrotic) type of cancer cell death. Furthermore, this mode of destruction of antibody-opsonized cancer cells by neutrophils is potentiated by CD47-SIRPα checkpoint blockade. Collectively, these findings show that neutrophil ADCC toward cancer cells occurs by a mechanism of cytotoxicity called trogoptosis, which can be further improved by targeting CD47-SIRPα interactions.

Dynamics of Transcription Regulation in Human Bone Marrow Myeloid Differentiation to Mature Blood Neutrophils

Neutrophils are short-lived blood cells that play a critical role in host defense against infections. To better comprehend neutrophil functions and their regulation, we provide a complete epigenetic overview, assessing important functional features of their differentiation stages from bone marrow-residing progenitors to mature circulating cells. Integration of chromatin modifications, methylation, and transcriptome dynamics reveals an enforced regulation of differentiation, for cellular functions such as release of proteases, respiratory burst, cell cycle regulation, and apoptosis. We observe an early establishment of the cytotoxic capability, while the signaling components that activate these antimicrobial mechanisms are transcribed at later stages, outside the bone marrow, thus preventing toxic effects in the bone marrow niche. Altogether, these data reveal how the developmental dynamics of the chromatin landscape orchestrate the daily production of a large number of neutrophils required for innate host defense and provide a comprehensive overview of differentiating human neutrophils.

Activation of cryptic splice sites in three patients with chronic granulomatous disease

Background

Chronic granulomatous disease (CGD) is a primary immune deficiency caused by mutations in the genes encoding the structural components of the phagocyte NADPH oxidase. As a result, the patients cannot generate sufficient amounts of reactive oxygen species required for killing pathogenic microorganisms.

Methods

We analyzed NADPH oxidase activity and component expression in neutrophils, performed genomic DNA and cDNA analysis, and used mRNA splicing prediction tools to evaluate the impact of mutations.

Results

In two patients with CGD, we had previously found mutations that cause aberrant pre‐mRNA splicing. In one patient an exonic mutation in a cryptic donor splice site caused the deletion of the 3' part of exon 6 from the mRNA of CYBB. This patient suffers from X‐linked CGD. The second patient, with autosomal CGD, has a mutation in the donor splice site of intron 1 of CYBA that activates a cryptic donor splice site downstream in intron 1, causing the insertion of intronic sequences in the mRNA. The third patient, recently analyzed, also with autosomal CGD, has a mutation in intron 4 of CYBA, 15 bp from the acceptor splice site. This mutation weakens a branch site and activates a cryptic acceptor splice site, causing the insertion of 14 intronic nucleotides into the mRNA.

Conclusion

We found three different mutations, one exonic, one in a donor splice site and one intronic, that all caused missplicing of pre‐mRNA. We analyzed these mutations with four different splice prediction programs and found that predictions of splice site strength, splice enhancer and splice silencer protein binding and branch site strength are all essential for correct prediction of pre‐mRNA splicing.

Yield of staging laparoscopy before treatment of locally advanced pancreatic cancer to detect occult metastases

INTRODUCTION

Locally advanced pancreatic cancer (LAPC) is found in 35% of patients with pancreatic cancer. However, these patients often have occult metastatic disease. Patients with occult metastases are unlikely to benefit from locoregional treatments. This study evaluated the yield of occult metastases during staging laparoscopy in patients with LAPC.

METHODS

Between January 2013 and January 2017 all patients with LAPC underwent a staging laparoscopy after a recent tri-phasic CT-scan of the chest and abdomen. Data were retrospectively reviewed from a prospectively maintained database. Univariate and multivariable logistic regression analysis was conducted to predict metastasis found at laparoscopy.

RESULTS

A total of 91 (41% male, median age 64 years) LAPC patients were included. The median time between CT-scan and staging laparoscopy was 21 days. During staging laparoscopy metastases were found in 17 patients (19%, 95% CI: 12%-28%). Seven (8%) patients had liver-only, 9 (10%) patients peritoneal-only, and 1 (1%) patient both liver and peritoneal metastases. Univariate logistic regression analysis showed that CEA (OR 1.056, 95% CI 1.007-1.107, p = 0.02) was the only preoperative predictor for occult metastases. In a multivariable logistic regression analysis of the preoperative risk factors again only CEA was an independent predictor for occult metastatic disease (p = 0.03). Patients with a CEA above 5 μg/L had a risk of occult metastasis of 91%. FOLFIRINOX was given to 69 (76%) of the patients with a median number of cycles of 8. Subsequent radiotherapy was given to 44 (48%) patients after the FOLFIRINOX treatment. Six (14%) patients underwent a resection after FOLFIRINOX and radiotherapy. The overall 1-year survival was 53% in patients without occult metastasis versus 29% with occult metastasis (p = 0.11). The 1-year OS for patients that completed FOLFIRINOX and radiotherapy was 84%.

CONCLUSION

The yield of staging laparoscopy for occult intrahepatic or peritoneal metastases in patients with locally advanced pancreatic cancer was 19%. Staging laparoscopy is recomended for patients with LAPC for accurate staging to determine optimal treatment.

Characterization of two novel mutations in IL-12R signaling in MSMD patients

Mendelian Susceptibility to Mycobacterial Disease (MSMD) is a rare syndrome with infections-among other complications-after Bacillus Calmette-Guerin (BCG) vaccination in children. We focused on the IL-12/IFN-γ pathway to identify new mutations in our patients. This study included 20 patients by vulnerability to mycobacteria and clinical manifestations of severe, recurrent infections. Blood samples were activated with BCG, BCG + IL-12 and BCG + IFN-γ. Cytokine levels were analyzed by ELISA. Measurements of IL-12Rβ1 and IL-12Rβ2 on the surface of peripheral blood mononuclear cells were performed by flow cytometry. To detect genetic defects, next-generation sequencing was performed by Thermo Fisher immunodeficiency panel. Flow cytometry analysis of 20 patients indicated reduction in IL-12R (β1/β2) expression in seven patients who showed incomplete production of IFN-γ by ELISA. In the patient with reduced IL-12 production, IFN-γR and IL-12R (β1/β2) expression levels were normal. Mutation analysis showed three previously reported mutations, two novel mutations in IL-12 R (β1/β2), and one previously reported mutation in IL-12.

Common Infections and Target Organs Associated with Chronic Granulomatous Disease in Iran

Recurrent severe bacterial and fungal infections are characteristic features of the rare genetic immunodeficiency disorder chronic granulomatous disease (CGD). The disease usually manifests within the first years of life with an incidence of 1 in approximately 200,000 live births. The incidence is higher in Iran and Morocco where it reaches 1.5 per 100,000 live births. Mutations have been described in the 5 subunits of NADPH oxidase, mostly in gp91phox and p47phox, with fewer mutations reported in p67phox, p22phox, and p40phox. These mutations cause loss of superoxide production in phagocytic cells. CYBB, the gene encoding the large gp91phox subunit of the transmembrane component cytochrome b558 of the NADPH oxidase complex, is localized on the X-chromosome. Genetic defects in CYBB are responsible for the disease in the majority of male CGD patients. CGD is associated with the development of granulomatous reactions in the skin, lungs, bones, and lymph nodes, and chronic infections may be seen in the liver, gastrointestinal tract, brain, and eyes. There is usually a history of repeated infections, including inflammation of the lymph glands, skin infections, and pneumonia. There may also be a persistent runny nose, inflammation of the skin, and inflammation of the mucous membranes of the mouth. Gastrointestinal problems can also occur, including diarrhea, abdominal pain, and perianal abscesses. Infection of the bones, brain abscesses, obstruction of the genitourinary tract and/or gastrointestinal tract due to the formation of granulomatous tissue, and delayed growth are also symptomatic of CGD. The prevention of infectious complications in patients with CGD involves targeted prophylaxis against opportunistic microorganisms such as Staphylococcus aureus, Klebsiella spp., Salmonella spp. and Aspergillus spp. In this review, we provide an update on organ involvement and the association with specific isolated microorganisms in CGD patients.

Chronic Granulomatous Disease

Chronic granulomatous disease is a clinical condition that stems from inactivating mutations in NOX2 and its auxiliary proteins. Together, these proteins form the phagocyte NADPH oxidase enzyme that generates superoxide. Superoxide (O₂^ċ-) and its reduced product hydrogen peroxide (H₂O₂) give rise to several additional reactive oxygen species (ROS), which together are necessary for adequate killing of pathogens. Thus, CGD patients, with a phagocyte NADPH oxidase that is not properly functioning, suffer from recurrent, life-threatening infections with certain bacteria, fungi, and yeasts. Here, I give a short survey of the genetic mutations that underlie CGD, the effect of these mutations on the activity of the leukocyte NADPH oxidase, the clinical symptoms of CGD patients, and the treatment options for these patients.

An adult autosomal recessive chronic granulomatous disease patient with pulmonary Aspergillus terreus infection

Background

Genetic mutations that reduce intracellular superoxide production by granulocytes causes chronic granulomatous disease (CGD). These patients suffer from frequent and severe bacterial and fungal infections throughout their early life. Diagnosis is usually made in the first 2 years of life but is sometimes only diagnosed when the patient is an adult although they may have suffered from symptoms since childhood.

Case presentation

A 26-year-old man was referred with weight loss, fever, hepatosplenomegaly and coughing. He had previously been diagnosed with lymphadenopathy in the neck at age 8 and prescribed anti-tuberculosis treatment. A chest radiograph revealed extensive right-sided consolidation along with smaller foci of consolidation in the left lung. On admission to hospital he had respiratory problems with fever. Laboratory investigations including dihydrorhodamine-123 (DHR) tests and mutational analysis indicated CGD. Stimulation of his isolated peripheral blood neutrophils (PMN) with phorbol 12-myristate 13-acetate (PMA) produced low, subnormal levels of reactive oxygen species (ROS). Aspergillus terreus was isolated from bronchoalveolar lavage (BAL) fluid and sequenced.

Conclusions

We describe, for the first time, the presence of pulmonary A. terreus infection in an adult autosomal CGD patient on long-term corticosteroid treatment. The combination of the molecular characterization of the inherited CGD and the sequencing of fungal DNA has allowed the identification of the disease-causing agent and the optimal treatment to be given as a consequence.

Retrotransposable genetic elements causing neutrophil defects

BACKGROUND

Retrotransposable elements are stretches of DNA that encode proteins with the inherent ability to insert their own RNA or another RNA by reverse transcriptase as DNA into a new genomic location. In humans, the only autonomous retrotransposable elements are members of the Long INterspersed Element-1 (LINE-1) family. LINE-1s may cause gene inactivation and human disease.

DESIGN

We present a brief summary of the published knowledge about LINE-1s in humans and the RNAs that these elements can transpose, and we focus on the effect of LINE-1-mediated retrotransposition on human neutrophil function.

RESULTS

Retrotransposons can cause genetic disease by two primary mechanisms: (1) insertional mutagenesis and (2) nonallelic homologous recombination. The only known neutrophil function affected by retrotransposition is that of NADPH oxidase activity. Four patients with chronic granulomatous disease (CGD) are known with LINE-1-mediated insertional inactivation of CYBB, the gene that encodes the gp91^phox component of the phagocyte NADPH oxidase. In addition, 5 CGD patients had a large deletion in the NCF2 gene, encoding the p67^phox component, and 2 CGD patients had a similar deletion in NCF1, encoding p47^phox . These deletions were caused by nonallelic homologous recombination between 2 Alu elements at the borders of each deletion. Alu elements have spread throughout the human genome by LINE-1 retrotransposition.

CONCLUSIONS

Probably, the occurrence of LINE-1-mediated insertions causing autosomal CGD has been underestimated. It might be worthwhile to reinvestigate the DNA from autosomal CGD patients with missplice mutations and large deletions for indications of LINE-1-mediated insertions.

Inherited p40phox deficiency differs from classic chronic granulomatous disease

Biallelic loss-of-function (LOF) mutations of the NCF4 gene, encoding the p40phox subunit of the phagocyte NADPH oxidase, have been described in only 1 patient. We report on 24 p40phox-deficient patients from 12 additional families in 8 countries. These patients display 8 different in-frame or out-of-frame mutations of NCF4 that are homozygous in 11 of the families and compound heterozygous in another. When overexpressed in NB4 neutrophil-like cells and EBV-transformed B cells in vitro, the mutant alleles were found to be LOF, with the exception of the p.R58C and c.120_134del alleles, which were hypomorphic. Particle-induced NADPH oxidase activity was severely impaired in the patients' neutrophils, whereas PMA-induced dihydrorhodamine-1,2,3 (DHR) oxidation, which is widely used as a diagnostic test for chronic granulomatous disease (CGD), was normal or mildly impaired in the patients. Moreover, the NADPH oxidase activity of EBV-transformed B cells was also severely impaired, whereas that of mononuclear phagocytes was normal. Finally, the killing of Candida albicans and Aspergillus fumigatus hyphae by neutrophils was conserved in these patients, unlike in patients with CGD. The patients suffer from hyperinflammation and peripheral infections, but they do not have any of the invasive bacterial or fungal infections seen in CGD. Inherited p40phox deficiency underlies a distinctive condition, resembling a mild, atypical form of CGD.

Loss of Thrombin-Induced Ca2+ Mobilization in a Subpopulation of Platelets during Storage

Thrombin-induced changes in cytosolic free Ca2+ ([Ca2+]i) were studied in human platelets that had been stored for up to 6 days. Changes in [Ca2+]i were measured with Indo-1-loaded platelets and quantitated with two different methods: (i) measurement of the changes in total fluorescence; (ii) measurement of the [Ca2+]i changes in individual platelets in a flow cytometer, allowing the detection of non-responding platelets. The maximal concentration of [Ca2+]i after stimulation with 0.5 U of thrombin/ml decreased from 544 ± 58 nM (mean ± SEM, n = 6) on day 0, to 276 ± 9 nM on day 3 and to 203 ± 23 nM on day 6. The percentage of platelets responding to 0.5 U of thrombin/ml declined from 90 ± 2% on day 0 to 72 ± 4% on day 3, and to 47 ± 8% on day 6. Nevertheless, also the responding platelets showed a decreased rise in [Ca2+]i.

The study shows that during platelet storage a decrease in the rise in [Ca2+]i upon thrombin stimulation occurs. This decrease is partly due to the formation of a subpopulation of platelets that is completely unresponsive and partly due to a decreased responsiveness in the remainder of the platelets; it is not due to a gradual decline in [Ca2+]i rise in all platelets. This phenomenon provides new insight in the functional defect of stored platelets.

Stored Platelets Release Nucleotides as Inhibitors of Platelet Function

It is well known that the function of platelets decreases progressively during storage of platelet concentrates at room temperature. To investigate this phenomenon in more detail, we have resuspended platelets that had been stored for 24 h or 72 h in fresh plasma, and we have measured the aggregation response and the ATP secretion. Conversely, the effect of plasma in which platelet concentrates (PC) had been stored for 24 h or 72 h, was tested on fresh platelets. Both the aggregation response to collagen and ADP and the collagen-induced ATP secretion of stored platelets partially recovered after incubation with fresh plasma (p <0.05). The same parameters measured with fresh platelets incubated in stored PC-plasma were found to be significantly reduced in comparison with the response of fresh platelets in fresh plasma (p <0.05). Finally, platelets were stored in a plasma-free medium, suitable for platelet storage and the supernatant was tested. This supernatant inhibited the function of fresh platelets in a storage time-dependent fashion. Boiling of these supernatants did not change the inhibiting capacities, whereas filtration over active charcoal did. Analysis of this supernatant revealed AMP and diadenosine tetraphosphate, which both inhibit platelet function.

These data show that stored platelets release nucleotides that inhibit platelet function in a reversible manner. This phenomenon may contribute to the decrease of platelet function during storage and the recovery of platelet function after transfusion.

Depletion of Dense Granule Nucleotides during Storage of Human Platelets

The energy metabolism of human platelets was studied during storage of platelet concentrates. The platelets were prepared from buffy coats in PVC/DEHP bags and stored for 7 days at room temperature at a concentration of 1.0 × 109/ml with horizontal agitation. The total amount of ATP and ADP decreased with 40% during this storage. This decrease correlated with the disc-tosphere transformation associated with the loss of platelet viability. During storage, the ability to incorporate 3H-adenosine into metabolic ATP and ADP (45 min at 37° C) decreased with 50%. Via measurement of the specific activity of actin-bound ADP and the amount of incorporated radioactivity into total ATP and ADP, we calculated the content of the metabolic and storage pools of ATP and ADP. The results indicate that the decrease in adenine nucleotide levels during storage was mainly caused by a depletion of ATP and ADP from the storage pool, whereas the metabolic pool remained nearly intact. After 7 days, the ATP : ADP ratio of the storage pool had decreased from 1.0 to 0.3, indicating hydrolysis of ATP.

Diadenosine-triphosphate and diadenosine-tetraphosphate (present in the storage pool) decreased with only 30%, and the serotonin content remained nearly constant. Therefore, it is unlikely that the storage pool was completely secreted. Probably, the storage pool of nucleotides serves as an internal supply for maintaining the contents of the metabolic pool of ATP and ADP during storage of platelets.

Analysis of Chronic Granulomatous Disease in the Kavkazi Population in Israel Reveals Phenotypic Heterogeneity in Patients with the Same NCF1 mutation (c.579G>A)

PURPOSE

Chronic granulomatous disease (CGD) is an innate immune deficiency disorder of phagocytes, resulting from mutations in the components of the NADPH oxidase complex that impair the synthesis of oxygen radicals, thus rendering patients susceptible to recurrent infections and excessive hyperinflammatory responses. The most common autosomal recessive form of CGD is p47^phox deficiency, which is often clinically milder than the more common X-linked recessive form. Here, we report data on genetics, clinical and biochemical findings in 17 CGD patients of Kavkazi origin with the nonsense mutation c.579G>A in the NCF1 gene, leading to p47^phox deficiency.

METHODS

Diagnosis was based on detailed clinical evaluation, respiratory burst activity by cytochrome c reduction and dihydrorhodamine-1,2,3 (DHR) assay by flow cytometry, expression of p47^phox by immunoblotting and molecular confirmation by DNA sequence analysis.

RESULTS

Twelve male and five female patients with median age at onset of 2.5 years (range 1 day to 9 years) were included in the study. The present cohort displays an encouraging 88% overall long-term survival, with median follow-up of 17 years. Clinical manifestations varied from mild to severe expression of the disease. Correlation between genotype and phenotype is unpredictable, although the Kavkazi patients were more severely affected than other patients with p47^phox deficiency.

CONCLUSIONS

Kavkazi CGD patients harbor a common genetic mutation that is associated with a heterogeneous clinical phenotype. Early diagnosis and proper clinical management in an experienced phagocytic leukocyte center is imperative to ensure favorable patient outcome. New treatment strategies are ongoing, but results are not yet conclusive.

A false-carrier state for the c.579G>A mutation in the NCF1 gene in Ashkenazi Jews

BACKGROUND

Mutations in the NCF1 gene that encodes p47^phox, a subunit of the NADPH oxidase complex, cause chronic granulomatous disease (CGD). In Kavkazi Jews, a c.579G>A (p.Trp193Ter) mutation in NCF1 is frequently found, leading to CGD. The same mutation is found in about 1% of Ashkenazi Jews, although Ashkenazi CGD patients with this mutation have never been described.

METHODS

We used Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), gene scan analysis and Ion Torrent Next Generation Sequencing for genetic analysis, and measured NADPH oxidase activity and p47^phox expression.

RESULTS

In an Ashkenazi couple expecting a baby, both parents were found to be heterozygotes for this mutation, as was the fetus. However, segregation analysis in the extended family was consistent with the fetus inheriting both carrier alleles from the parents. MLPA indicated four complete NCF1 genes in the fetus and three in each parent. Gene sequencing confirmed these results. Analysis of fetal leucocytes obtained by cordocentesis revealed substantial oxidase activity with three different assays, which was confirmed after birth. In six additional Ashkenazi carriers of the NCF1 c.579G>A mutation, we found five individuals with three complete NCF1 genes of which one was mutated (like the parents), and one individual with in addition a fusion gene of NCF1 with a pseudogene.

CONCLUSION

These results point to the existence of a 'false-carrier' state in Ashkenazi Jews and have wide implications regarding pre-pregnancy screening in this and other population groups.

Very early onset inflammatory bowel disease: Investigation of the IL-10 signaling pathway in Iranian children

BACKGROUND & AIM

Comparing to adult inflammatory bowel disease (IBD), those with early onset manifestations have different features in terms of the underlying molecular pathology, the course of disease and the response to therapy. We investigated the IL-10 signaling pathway previously reported as an important cause of infantile (Very Early Onset) IBD to find any possible variants.

METHOD

With the next generation sequencing technique we screened IL-10, IL-10RA and IL10RB genes of 15 children affected by very early onset-GI (gastrointestinal) disorders. Additionally, we analyzed them based on Thermo Fisher immune deficiency panel for genes either having a known role in IBD pathogenesis or cause the disorders with overlapping manifestations. We performed multiple functional analyses only for the cases showing variants in IL-10- related genes.

RESULT

In 3 out of 15 patients we identified variants including a homozygous and heterozygote mutations in IL-10RA and a novel homozygous mutation in IL-12RB1. Our functional studies reveal that in contrast to the IL-10RA heterozygote mutation that does not have deleterious effects, the homozygous mutation abrogates the IL-10 signaling pathway.

CONCLUSION

Our study suggests we need to modify the classical diagnostic approach from functional assays followed by candidate- gene or genes sequencing to the firstly parallel genomic screening followed by functional studies.

How neutrophils kill fungi

Neutrophils play a critical role in the prevention of invasive fungal infections. Whereas mouse studies have demonstrated the role of various neutrophil pathogen recognition receptors (PRRs), signal transduction pathways, and cytotoxicity in the murine antifungal immune response, much less is known about the killing of fungi by human neutrophils. Recently, novel primary immunodeficiencies have been identified in patients with a susceptibility to fungal infections. These human 'knock-out' neutrophils expand our knowledge to understand the role of PRRs and signaling in human fungal killing. From the studies with these patients it is becoming clear that neutrophils employ fundamentally distinct mechanisms to kill Candida albicans or Aspergillus fumigatus.

Mutation characterization and heterodimer analysis of patients with leukocyte adhesion deficiency: Including one novel mutation

BACKGROUND AND AIM

Leukocyte adhesion deficiency type 1 (LAD-I) is a rare, autosomal recessive disorder of neutrophil migration, characterized by severe, recurrent bacterial infections, inadequate pus formation and impaired wound healing. The ITGB2 gene encodes the β2 integrin subunit (CD18) of the leukocyte adhesion cell molecules, and mutations in this gene cause LAD-I. The aim of the current study was to investigate the mutations in patients diagnosed with LAD-I and functional studies of the impact of two previously reported and a novel mutation on the expression of the CD18/CD11a heterodimer.

MATERIALS AND METHODS

Blood samples were taken from three patients who had signed the consent form. Genomic DNA was extracted and ITGB2 exons and flanking intronic regions were amplified by polymerase chain reaction. Mutation screening was performed after Sanger sequencing of PCR products. For functional studies, COS-7 cells were co-transfected with an expression vector containing cDNA encoding mutant CD18 proteins and normal CD11a. Flow cytometry analysis of CD18/CD11a expression was assessed by dimer-specific IB4 monoclonal antibody.

RESULTS

Two previously reported mutations and one novel mutation,p. Cys562Tyr, were found. All mutations reduced CD18/CD11 heterodimer expression.

CONCLUSION

Our strategy recognized the p.Cys562Tyr mutation as a pathogenic alteration that does not support CD18 heterodimer formation. Therefore, it can be put into a panel of carrier and prenatal diagnosis programs.

Chronic granulomatous disease: Clinical, functional, molecular, and genetic studies. The Israeli experience with 84 patients

Chronic granulomatous disease (CGD) is an innate immunodeficiency with a genetic defect of the nicotinamide adenosine dinucleotide phosphate, reduced, oxidase components. This leads to decreased reactive oxygen species (ROS) production, which renders patients susceptible to life-threatening infections. Over the course of 30 years, we diagnosed CGD in 84 patients from 61 families using functional, molecular, and genetic studies. The incidence of CGD in Israel is 1.05 per 100,000 live-births in the Jewish population and 1.49 in the Israeli Arab population. We diagnosed 52 patients (62%) with autosomal recessive inheritance (AR-CGD) and 32 (38%) with X-linked recessive inheritance (XLR-CGD). Consanguinity was detected in 64% of AR-CGD families (14% in Jews and 50% in Israeli Arabs). We found 36 different mutations (23 in XLR-CGD and 13 in AR-CGD patients), 15 of which were new. The clinical spectrum of CGD varied from mild to severe disease in both XLR and AR forms, although the AR subtype is generally milder. Further, residual ROS production correlated with milder clinical expression, better prognosis and improved overall survival. Patients with recurrent pyogenic infections developed fibrosis and hyperinflammatory states with granuloma formation. The management of CGD has progressed substantially in recent years, evolving from a fatal disease of early childhood to one of long-term survival. Our present cohort displays an encouraging 81% overall long term survival. Early hematopoietic stem cell transplantation is advisable before tissue damage is irreversible. Successful transplantation was performed in 18/21 patients. Therapeutic gene modification could become an alternative cure for CGD. Am. J. Hematol. 92:28-36, 2017. © 2016 Wiley Periodicals, Inc.

Gene mutations responsible for primary immunodeficiency disorders: A report from the first primary immunodeficiency biobank in Iran

BACKGROUND

Primary immunodeficiency (PID) is a heterogeneous group of inheritable genetic disorders with increased susceptibility to infections, autoimmunity, uncontrolled inflammation and malignancy. Timely precise diagnosis of these patients is very essential since they may not be able to live with their congenital immunity defects; otherwise, they could survive with appropriate treatment. DNA biobanks of such patients could be used for molecular and genetic testing, facilitating the detection of underlying mutations in known genes as well as the discovery of novel genes and pathways.

METHODS

According to the last update of the International Union of Immunological Societies (IUIS) classification, patients are registered in our biobank during a period of 15 years. All patients' data were collected via questionnaire and their blood samples were taken in order to extract and protect their DNA content.

RESULTS

Our study comprised 197 patients diagnosed with PID. Antibody deficiency in 50 patients (25.4%), phagocytic defect in 47 patients (23.8%) and combined immunodeficiency with associated/syndromic feature in 19 patients (9.6%) were the most common PID diagnoses, respectively. The most common variant of PID in our study is common variable immunodeficiency, which accounted for 20 cases (10.1%), followed by chronic mucocutaneous candidiasis in 15 patients (7.9%) and congenital neutropenia in 13 patients (7%). Mean age at onset of disease was 4 years and mean age of diagnosis was 9.6 years. The average diagnostic delay was 5.5 years, with a range of 6 months to 46 years. Parental consanguinity and history of PID in family were observed in 70.2 and 48.9% of the patients, respectively. The majority of PID patients (93.3%) were from families with low socioeconomic status.

CONCLUSION

This prospective study was designed to establish a PID Biobank in order to have a high quality DNA reservoir of these patients, shareable for international diagnostic and therapeutic collaborations. This article emphasizes the need to raise the awareness of society and general practitioners to achieve timely diagnosis of these patients and prevent current mismanagements.

Chronic granulomatous disease

INTRODUCTION

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by recurrent, life-threatening bacterial and fungal infections of the skin, the airways, the lymph nodes, the liver, the brain and the bones. Frequently found pathogens are Staphylococcus aureus, Aspergillus species, Klebsiella species, Burkholderia cepacia, Serratia marcescens and Salmonella species.

SOURCES OF DATA

CGD is a rare (∼1:250 000 individuals) disease caused by mutations in any one of the five components of the NADPH oxidase in phagocytic leucocytes. This enzyme generates superoxide and is essential for intracellular killing of pathogens by phagocytes.

AREAS OF AGREEMENT

CGD patients suffer not only from life-threatening infections, but also from excessive inflammatory reactions.

AREAS OF CONTROVERSY

Neither the cause of these inflammatory reactions nor the way to treat them is clear.

AREAS TIMELY FOR DEVELOPING RESEARCH

Patient selection for and timing of bone marrow transplantation along with gene therapy.

Complement and phagocytes - A complicated interaction

Mohamed Daha and I share a common interest in innate immunity. Working in institutes only 25 miles away from each other, that meant ample opportunity and relevance for collaboration. And so we did. Moreover, we have both been members of boards and councils of Dutch national organizations, and we have also become good friends. In this short recollection, I look back on 40 years of common activities in complement research and friendship.

Impaired killing of Candida albicans by granulocytes mobilized for transfusion purposes: a role for granule components

Granulocyte transfusions are used to treat neutropenic patients with life-threatening bacterial or fungal infections that do not respond to anti-microbial drugs. Donor neutrophils that have been mobilized with granulocyte-colony stimulating factor (G-CSF) and dexamethasone are functional in terms of antibacterial activity, but less is known about their fungal killing capacity. We investigated the neutrophil-mediated cytotoxic response against C. albicans and A. fumigatus in detail. Whereas G-CSF/dexamethasone-mobilized neutrophils appeared less mature as compared to neutrophils from untreated controls, these cells exhibited normal ROS production by the NADPH oxidase system and an unaltered granule mobilization capacity upon stimulation. G-CSF/dexamethasone-mobilized neutrophils efficiently inhibited A. fumigatus germination and killed Aspergillus and Candida hyphae, but the killing of C. albicans yeasts was distinctly impaired. Following normal Candida phagocytosis, analysis by mass spectrometry of purified phagosomes after fusion with granules demonstrated that major constituents of the antimicrobial granule components, including major basic protein (MBP), were reduced. Purified MBP showed candidacidal activity, and neutrophil-like Crisp-Cas9 NB4-KO-MBP differentiated into phagocytes were impaired in Candida killing. Together, these findings indicate that G-CSF/dexamethasone-mobilized neutrophils for transfusion purposes have a selectively impaired capacity to kill Candida yeasts, as a consequence of an altered neutrophil granular content.

Human Neutrophils Use Different Mechanisms To Kill Aspergillus fumigatus Conidia and Hyphae: Evidence from Phagocyte Defects

Neutrophils are known to play a pivotal role in the host defense against Aspergillus infections. This is illustrated by the prevalence of Aspergillus infections in patients with neutropenia or phagocyte functional defects, such as chronic granulomatous disease. However, the mechanisms by which human neutrophils recognize and kill Aspergillus are poorly understood. In this work, we have studied in detail which neutrophil functions, including neutrophil extracellular trap (NET) formation, are involved in the killing of Aspergillus fumigatus conidia and hyphae, using neutrophils from patients with well-defined genetic immunodeficiencies. Recognition of conidia involves integrin CD11b/CD18 (and not dectin-1), which triggers a PI3K-dependent nonoxidative intracellular mechanism of killing. When the conidia escape from early killing and germinate, the extracellular destruction of the Aspergillus hyphae needs opsonization by Abs and involves predominantly recognition via Fcγ receptors, signaling via Syk, PI3K, and protein kinase C to trigger the production of toxic reactive oxygen metabolites by the NADPH oxidase and myeloperoxidase. A. fumigatus induces NET formation; however, NETs did not contribute to A. fumigatus killing. Thus, our findings reveal distinct killing mechanisms of Aspergillus conidia and hyphae by human neutrophils, leading to a comprehensive insight in the innate antifungal response.