Helicobacter pylori-infected human neutrophils exhibit impaired chemotaxis and a uropod retraction defect.

Helicobacter pylori is a major human pathogen that colonizes the gastric mucosa and plays a causative role in development of peptic ulcers and gastric cancer. Neutrophils are heavily infected with this organism in vivo and play a prominent role in tissue destruction and disease. Recently, we demonstrated that H. pylori exploits neutrophil plasticity as part of its virulence strategy eliciting N1-like subtype differentiation that is notable for profound nuclear hypersegmentation. We undertook this study to test the hypothesis that hypersegmentation may enhance neutrophil migratory capacity. However, EZ-TAXIScan™ video imaging revealed a previously unappreciated and progressive chemotaxis defect that was apparent prior to hypersegmentation onset. Cell speed and directionality were significantly impaired to fMLF as well as C5a and IL-8. Infected cells oriented normally in chemotactic gradients, but speed and direction were impaired because of a uropod retraction defect that led to cell elongation, nuclear lobe trapping in the contracted rear and progressive narrowing of the leading edge. In contrast, chemotactic receptor abundance, adhesion, phagocytosis and other aspects of cell function were unchanged. At the molecular level, H. pylori phenocopied the effects of Blebbistatin as indicated by aberrant accumulation of F-actin and actin spikes at the uropod together with enhanced ROCKII-mediated phosphorylation of myosin IIA regulatory light chains at S19. At the same time, RhoA and ROCKII disappeared from the cell rear and accumulated at the leading edge whereas myosin IIA was enriched at both cell poles. These data suggest that H. pylori inhibits the dynamic changes in myosin IIA contractility and front-to-back polarity that are essential for chemotaxis. Taken together, our data advance understanding of PMN plasticity and H. pylori pathogenesis.

Campylobacter jejuni induces differentiation of human neutrophils to the CD16hi /CD62Llo subtype.

The discovery of neutrophil subtypes has expanded what is known about neutrophil functions, yet there is still much to learn about the role of these subtypes during bacterial infection. We investigated whether Campylobacter jejuni induced differentiation of human neutrophils into the hypersegmented, CD16hi /CD62Llo subtype. In addition, we investigated whether C. jejuni-dependent differentiation of this neutrophil subtype induced cancer-promoting activities of human T cells and colonocytes, which were observed in other studies of hypersegmented, CD16hi /CD62Llo neutrophils. We found that C. jejuni causes a significant shift in human neutrophil populations to the hypersegmented, CD16hi /CD62Llo subtype and that those populations exhibit delayed apoptosis, elevated arginase-1 expression, and increased reactive oxygen species production. Furthermore, incubation of C. jejuni-infected neutrophils with human T cells resulted in decreased expression of the ζ-chain of the TCR, which was restored upon supplementation with exogenous l-arginine. In addition, incubation of C. jejuni-infected neutrophils with human colonocytes resulted in increased HIF-1α stabilization and NF-κB activation in those colonocytes, which may result in the up-regulation of protumorigenic genes.

Specific Granule Deficiency Due To Novel Homozygote SMARCD2 Variant.

Background: Specific granule deficiency (SGD) is a rare immunodeficiency associated with CCAT/enhancer-binding protein epsilon (CEBPE) gene variants. It can cause severe recurrent infections and is lethal without successful stem cell transplantation. Few cases with SGD of both type 1 and type 2 have been described in the literature. In this study, we present the first report of a case with a novel homozygous c.511 C > T (p.Gln171Ter) mutation in the SMARCD2 gene of SGD type 2, which was successfully treated with bone marrow transplantation. Case: A male infant presented to our neonatal intensive care unit on the second day of life with an icteric appearance and mild hypotonia. He was evaluated for immunodeficiency as the cause of delayed cord separation and refractory neutropenia. At 6 weeks of age, SGD type 2 with a new variant was diagnosed and successfully treated by bone marrow transplantation. Conclusion: SGD is an immunodeficiency disease that is quite rare. However, we believe that SGD diagnosis and associated new variants can be detected more frequently with the widespread use of all whole-exome sequencing techniques.

High Purity Isolation of Low Density Neutrophils Casts Doubt on Their Exceptionality in Health and Disease.

Low density neutrophils (LDNs) are described in a number of inflammatory conditions, cancers and infections and associated with immunopathology, and a mechanistic role in disease. The role of LDNs at homeostasis in healthy individuals has not been investigated. We have developed an isolation protocol that generates high purity LDNs from healthy donors. Healthy LDNs were identical to healthy normal density neutrophils (NDNs), aside from reduced neutrophil extracellular trap formation. CD66b, CD16, CD15, CD10, CD54, CD62L, CXCR2, CD47 and CD11b were expressed at equivalent levels in healthy LDNs and NDNs and underwent apoptosis and ROS production interchangeably. Healthy LDNs had no differential effect on CD4+ or CD8+ T cell proliferation or IFNγ production compared with NDNs. LDNs were generated from healthy NDNs in vitro by activation with TNF, LPS or fMLF, suggesting a mechanism of LDN generation in disease however, we show neutrophilia in people with Cystic Fibrosis (CF) was not due to increased LDNs. LDNs are present in the neutrophil pool at homeostasis and have limited functional differences to NDNs. We conclude that increased LDN numbers in disease reflect the specific pathology or inflammatory environment and that neutrophil density alone is inadequate to classify discrete functional populations of neutrophils.

Characterization of concurrent target suppression by JNJ-61178104, a bispecific antibody against human tumor necrosis factor and interleukin-17A.

Tumor necrosis factor (TNF) and interleukin (IL)-17A are pleiotropic cytokines implicated in the pathogenesis of several autoimmune diseases including rheumatoid arthritis (RA) and psoriatic arthritis (PsA). JNJ-61178104 is a novel human anti-TNF and anti-IL-17A monovalent, bispecific antibody that binds to both human TNF and human IL-17A with high affinities and blocks the binding of TNF and IL-17A to their receptors in vitro. JNJ-61178104 also potently neutralizes TNF and IL-17A-mediated downstream effects in multiple cell-based assays. In vivo, treatment with JNJ-61178104 resulted in dose-dependent inhibition of cellular influx in a human IL-17A/TNF-induced murine lung neutrophilia model and the inhibitory effects of JNJ-61178104 were more potent than the treatment with bivalent parental anti-TNF or anti-IL-17A antibodies. JNJ-61178104 was shown to engage its targets, TNF and IL-17A, in systemic circulation measured as drug/target complex formation in normal cynomolgus monkeys (cyno). Surprisingly, quantitative target engagement assessment suggested lower apparent in vivo target-binding affinities for JNJ-61178104 compared to its bivalent parental antibodies, despite their similar in vitro target-binding affinities. The target engagement profiles of JNJ-61178104 in humans were in general agreement with the predicted profiles based on cyno data, suggesting similar differences in the apparent in vivo target-binding affinities. These findings show that in vivo target engagement of monovalent bispecific antibody does not necessarily recapitulate that of the molar-equivalent dose of its bivalent parental antibody. Our results also offer valuable insights into the understanding of the pharmacokinetics/pharmacodynamics and target engagement of other bispecific biologics against dimeric and/or trimeric soluble targets in vivo.

Distinguishing Sepsis From Infection by Neutrophil Dysfunction: A Promising Role of CXCR2 Surface Level.

Sepsis is one of the well-established diseases with specific patterns of neutrophil dysfunctions. Previous studies demonstrated sepsis-related neutrophil dysfunctions in comparison with subjects without infection. Since sepsis and infection are recently recognized as distinctive processes, whether these neutrophil dysfunctions are associated with sepsis or infection are not known. Therefore, we longitudinally compared neutrophil functions, widely-cited as exhibiting sepsis-related changes, between patients with septic shock and infection. The surface level of cluster of differentiation 64 (CD64), C-C motif chemokine receptor 2 (CCR2), C-X-C motif chemokine receptor 2 (CXCR2); apoptosis; and NETosis were measured from peripheral blood neutrophils for seven consecutive days using flow cytometry. The between-group comparisons of neutrophil functions were made both on a day-by-day basis and as linear regression between time and measured neutrophil functions (sepsis status included as model predictors). Our study found that, among neutrophil functions studied, only CXCR2 surface level is associated with sepsis. At disease onset, CXCR2 level decrease, with a dose-response relationship with clinical severity. Its level reverts to resemble infected patients by the end of the week. The relationship between CD64 surface level, CCR2 surface level, NETosis, and sepsis are mediated through the effect of infection. Apoptosis activity between these groups are similar, hence, not sepsis-related.

Neutrophil Defects and Diagnosis Disorders of Neutrophil Function: An Overview.

Primary disorders of neutrophil function result from impairment in neutrophil responses that are critical for host defense. This chapter summarizes inherited disorders of neutrophils that cause defects in neutrophil adhesion, migration, and oxidative killing. These include the leukocyte adhesion deficiencies, actin defects and other disorders of chemotaxis, hyperimmunoglobulin E syndrome, Chédiak-Higashi Syndrome, neutrophil specific granule deficiency, chronic granulomatous disease, and myeloperoxidase deficiency. Diagnostic tests and treatment approaches are also summarized for each neutrophil disorder.

C/EBPε ΔRS derived from a neutrophil-specific granule deficiency patient interacts with HDAC1 and its dysfunction is restored by trichostatin A.

CCAAT/enhancer binding protein epsilon (C/EBPε), a myeloid-specific transcription factor, plays an important role in granulopoiesis. A loss-of-function mutation in this protein can result in an abnormal development of neutrophils and eosinophils, known as neutrophil-specific granule deficiency (SGD). The transcriptional activity of C/EBPε is regulated by interactions with other transcription factors and/or post-translational modification, including acetylation. Previously, we reported a novel SGD patient who had a homozygous mutation for two amino acids, arginine (R247) and serine (S248), which were deleted in the basic leucine zipper domain of C/EBPε (ΔRS) and exhibited loss of transcriptional activity with aberrant protein-protein interactions. In the present study, we found that a single amino acid deletion of either R247 (ΔR) or S248 (ΔS) was sufficient for the loss of C/EBPε transcriptional activity, while an amino acid substitution at S248 to alanine in C/EBPε (SA) had comparable transcriptional activity with the wild-type C/EBPε (WT). Although acetylation at lysine residues (K121 and K198) is indispensable for C/EBPε transcriptional activity, an acetylation mimic form of ΔRS (ΔRS-K121/198Q) did not exhibit the transcriptional activity. Interestingly, we discovered that ΔRS, ΔR, ΔS, and ΔRS-K121/198Q interacted with histone deacetylase 1 (HDAC1), whereas WT and SA did not. Furthermore, the proteoglycan 2/eosinophil major basic protein induction activity of ΔRS, ΔR, and ΔS could be restored by the HDAC inhibitor, trichostatin A (TSA), and protein-protein interactions between ΔRS and Gata1 could also be recovered by TSA treatment. Taken together, our results show that TSA has the potential to restore the transcriptional activity of ΔRS, indicating that the inhibition of HDAC1 could be a molecularly targeted treatment for SGD with ΔRS.

CEBPE-Mutant Specific Granule Deficiency Correlates With Aberrant Granule Organization and Substantial Proteome Alterations in Neutrophils.

Specific granule deficiency (SGD) is a rare disorder characterized by abnormal neutrophils evidenced by reduced granules, absence of granule proteins, and atypical bilobed nuclei. Mutations in CCAAT/enhancer-binding protein-ε (CEBPE) are one molecular etiology of the disease. Although C/EBPε has been studied extensively, the impact of CEBPE mutations on neutrophil biology remains elusive. Here, we identified two SGD patients bearing a previously described heterozygous mutation (p.Val218Ala) in CEBPE. We took this rare opportunity to characterize SGD neutrophils in terms of granule distribution and protein content. Granules of patient neutrophils were clustered and polarized, suggesting that not only absence of specific granules but also defects affecting other granules contribute to the phenotype. Our analysis showed that remaining granules displayed mixed protein content and lacked several glycoepitopes. To further elucidate the impact of mutant CEBPE, we performed detailed proteomic analysis of SGD neutrophils. Beside an absence of several granule proteins in patient cells, we observed increased expression of members of the linker of nucleoskeleton and cytoskeleton complex (nesprin-2, vimentin, and lamin-B2), which control nuclear shape. This suggests that absence of these proteins in healthy individuals might be responsible for segmented shapes of neutrophilic nuclei. We further show that the heterozygous mutation p.Val218Ala in CEBPE causes SGD through prevention of nuclear localization of the protein product. In conclusion, we uncover that absence of nuclear C/EBPε impacts on spatiotemporal expression and subsequent distribution of several granule proteins and further on expression of proteins controlling nuclear shape.

Deficiency of PI3-Kinase catalytic isoforms p110γ and p110δ in mice enhances the IL-17/G-CSF axis and induces neutrophilia.

BACKGROUND: Phosphoinositide 3-kinase γ (PI3Kγ) and PI3Kδ are second messenger-generating enzymes with key roles in proliferation, differentiation, survival, and function of leukocytes. Deficiency of the catalytic subunits p110γ and p110δ of PI3Kγ and PI3Kδ in p110γ/δ-/- mice leads to defective B- and T-cell homeostasis. Here we examined the role of p110γ and p110δ in the homeostasis of neutrophils by analyzing p110γ-/-, p110δ-/- and p110γ/δ-/- mice. METHODS: Neutrophils and T cells in leukocyte suspensions from the bone marrow (BM), blood, spleen and lung were analyzed by flow cytometry. Serum concentrations of IL-17, of the neutrophilic growth factor G-CSF, and of the neutrophil mobilizing CXC chemokines CXCL1/KC and CXCL2/MIP-2 were measured by Bio-Plex assay. Production of G-CSF and CXCL1/KC by IL-17-stimulated primary lung tissue cells were determined by ELISA, whereas IL-17-dependent signaling in lung tissue cells was analyzed by measuring Akt phosphorylation using immunoblot. RESULTS: We found that in contrast to single knock-out mice, p110γ/δ-/- mice exhibited significantly elevated neutrophil counts in blood, spleen, and lung. Increased granulocytic differentiation stages in the bone marrow of p110γ/δ-/- mice were paralleled by increased serum concentrations of G-CSF, CXCL1/KC, and CXCL2/MIP-2. As IL-17 induces neutrophilia via the induction of G-CSF and CXC chemokines, we measured IL-17 and IL-17-producing T cells. IL-17 serum concentrations and frequencies of IL-17+ splenic T cells were significantly increased in p110γ/δ-/- mice. Moreover, IFN-γ+, IL-4+, and IL-5+ T cell subsets were drastically increased in p110γ/δ-/- mice, suggesting that IL-17+ T cells were up-regulated in the context of a general percentage increase of other cytokine producing T cell subsets. CONCLUSIONS: We found that p110γ/δ deficiency in mice induces complex immunological changes, which might in concert contribute to neutrophilia. These findings emphasize a crucial but indirect role of both p110γ and p110δ in the regulation of neutrophil homeostasis.

Proposed diagnostic criteria and classification of basophilic leukemias and related disorders.

Basophils form a distinct cell lineage within the hematopoietic cell family. In various myeloid neoplasms, including chronic myeloid leukemia, basophilia is frequently seen. Acute and chronic basophilic leukemias, albeit rare, have also been described. However, no generally accepted criteria and classification of basophilic leukemias have been presented to date. To address this unmet need, a series of Working Conferences and other meetings were organized between March 2015 and March 2016. The current article provides a summary of consensus statements from these meetings, together with proposed criteria to delineate acute basophilic leukemia (ABL) from chronic basophilic leukemia (CBL) and primary forms of the disease where no preceding myeloid malignancy is detected, from the more common 'secondary' variants. Moreover, the term hyperbasophilia (HB) is proposed for cases with a persistent peripheral basophil count ⩾1000 per µl of blood. This condition, HB, is highly indicative of the presence of an underlying myeloid neoplasm. Therefore, HB is an important checkpoint in the diagnostic algorithm and requires a detailed hematologic investigation. In these patients, an underlying myeloid malignancy is often found and is then labeled with the appendix -baso, whereas primary cases of ABL or CBL are very rare. The criteria and classification proposed in this article should facilitate the diagnosis and management of patients with unexplained basophilia and basophil neoplasms in routine practice, and in clinical studies.

Retinoic acid induces hypersegmentation and enhances cytotoxicity of neutrophils against cancer cells.

Hypersegmentation of nuclei is considered a distinct characteristic of the antitumoral phenotype of neutrophils. Retinoic acid, a metabolite of retinol, reorganizes and induces segmentation of the nucleus during the differentiation of neutrophils. However, the role of retinoic acid in the phenotype polarization of neutrophils has not been fully established. Here, we investigated the effect of retinoic acid on phenotype polarization of neutrophils. Retinoic acid-induced the hypersegmentation of human neutrophils via retinoic acid receptors and mTOR pathways. Retinoic acid-induced hypersegmented neutrophils enhanced neutrophil extracellular traps (NETs) formation in response to phorbol-12-myristate 13-acetate (PMA) and fMLP (N-Formylmethionine-leucyl-phenylalanine) stimulation, and increased cytotoxicity against various tumor cells. Moreover, retinoic acid treatment attenuated tumor growth in a murine model of tumor. Taken together, these results suggests that retinoic acid induces the phenotype polarization of neutrophils to exert antitumor effects.

Frontline Science: HMGB1 induces neutrophil dysfunction in experimental sepsis and in patients who survive septic shock.

Sepsis is accompanied by the initial activation of proinflammatory pathways and long-lasting immunosuppression that appears to contribute to late-occurring mortality. Although high-mobility group box 1 (HMGB1) is involved in many aspects of inflammation, its role in sepsis-induced immune suppression remains unclear. In this study, we examined HMGB1's contribution to neutrophil NADPH oxidase activity dysfunction and associated neutrophil-dependent bacterial clearance in mice subjected to sepsis and in patients who survive septic shock. Using a murine model of polymicrobial septic peritonitis, we demonstrated that treatment with anti-HMGB1 Ab significantly diminished sepsis-induced dysfunction of neutrophil NADPH oxidase activity. In a subsequent set of experiments, we found that blocking HMGB1 preserved the ability of neutrophils from patients recovering from septic shock to activate NADPH oxidase. Taken together, our data suggest that HMGB1 accumulation in the late phase of sepsis plays a specific role in the development of postsepsis immunosuppression and specifically affects neutrophil-dependent antibacterial defense mechanisms. Thus, blocking HMGB1 may be a promising therapeutic intervention to diminish the adverse effects of sepsis-induced immunosuppression.

A proof-of-concept clinical study examining the NRF2 activator sulforaphane against neutrophilic airway inflammation.

UNLABELLED: Sulforaphane (SFN), a naturally occurring isothiocyanate found in cruciferous vegetables, is implicated as a possible therapy for airway inflammation via induction of the transcription factor NF-E2-related factor 2 (NRF2). In this proof-of-concept clinical study, we show that supplementation of SFN with broccoli sprout homogenate in healthy human subjects did not induce expression of antioxidant genes or protect against neutrophilic airway inflammation in an ozone-exposure model. Therefore, dietary sulforaphane supplementation is not a promising candidate for larger scale clinical trials targeting airway inflammation. TRIAL REGISTRATION: NCT01625130 . Registered 19 June, 2012.

Role of the Leucine Zipper Domain of CCAAT/ Enhancer Binding Protein-Epsilon (C/EBPε) in Neutrophil-Specific Granule Deficiency.

Neutrophil-specific granule deficiency (SGD) is a rare autosomal recessive primary immunodeficiency characterized by bilobed neutrophil nuclei and lack of neutrophil-specific granule proteins such as lactoferrin. A deficiency of a myeloid-specific transcription factor, CCAAT/enhancer binding protein-epsilon (C/EBPε), has been identified as a cause of SGD. C/EBPε binds to DNA though its basic leucine zipper (bZIP) domain, and regulates terminal differentiation of neutrophils and expression of specific granule genes. Homozygous frameshift mutations resulting in loss of the bZIP domain have been reported in two patients with SGD. A recent observation showed that a homozygous 2-aa deletion in the bZIP domain with normal DNA-binding and dimerization abilities causes SGD by impairing protein-protein interactions with other transcription factors, indicating that multiple molecular mechanisms can lead to SGD. Studies of patient-derived mutations and analysis of C/EBPε knockout mice have shown the importance of the bZIP domain for the essential functions of C/EBPε.

Genetic variation associates with susceptibility for cigarette smoke-induced neutrophilia in mice.

Neutrophilic airway inflammation is one of the major hallmarks of chronic obstructive pulmonary disease and is also seen in steroid resistant asthma. Neutrophilic airway inflammation can be induced by different stimuli including cigarette smoke (CS). Short-term exposure to CS induces neutrophilic airway inflammation in both mice and humans. Since not all individuals develop extensive neutrophilic airway inflammation upon smoking, we hypothesized that this CS-induced innate inflammation has a genetic component. This hypothesis was addressed by exposing 30 different inbred mouse strains to CS or control air for 5 consecutive days, followed by analysis of neutrophilic lung inflammation. By genomewide haplotype association mapping, we identified four susceptibility genes with a significant association to lung tissue levels of the neutrophil marker myeloperoxidase under basal conditions and an additional five genes specifically associated with CS-induced tissue MPO levels. Analysis of the expression levels of the susceptibility genes by quantitative RT-PCR revealed that three of the four genes associated with CS-induced tissue MPO levels had CS-induced changes in gene expression levels that correlate with CS-induced airway inflammation. Most notably, CS exposure induces an increased expression of the coiled-coil domain containing gene, Ccdc93, in mouse strains susceptible for CS-induced airway inflammation whereas Ccdc93 expression was decreased upon CS exposure in nonsusceptible mouse strains. In conclusion, this study shows that CS-induced neutrophilic airway inflammation has a genetic component and that several genes contribute to the susceptibility for this response.

Phosphatase Wip1 as a new therapeutic target for intestinal ischemia-reperfusion injury.

Intestinal ischemia/reperfusion (I/R) injury is a pathophysiology involving local tissue injury and organ dysfunction. Accumulating evidence has confirmed that the infiltration of neutrophils is of central importance in mediating intestinal I/R injury. On the other hand, adequate neutrophils in the intestine could also benefit the antibacterial translocation and tissue repair. Consequently, regulation of neutrophil immunity after intestinal I/R might be a promising therapy for controlling intestinal injury. Wip1 is a serine/threonine protein phosphatase that acts as the master regulator of tumorigenesis. However, emerging evidence highlights the importance of Wip1 in regulating neutrophil development, maturation, migration and neutrophil pro-inflammatory cytokine productions. Our recent studies showed that Wip1 negatively regulates neutrophil inflammatory responses and plays a protective role in intestinal I/R injury. In light of this discovery, we believe that Wip1 might be a new therapeutic target for treating intestinal I/R injury.

Hereditary erythrocytosis, thrombocytosis and neutrophilia.

Hereditary erythrocytosis, thrombocytosis, and neutrophilia are rare inherited syndromes which exhibit Mendelian inheritance. Some patients with primary hereditary erythrocytosis exhibit a mutation in the erythropoietin receptor (EPOR) which is associated with low serum erythropoietin (EPO) levels. Secondary congenital erythrocytosis may be characterized by normal or high serum EPO levels, and is related to high oxygen affinity haemoglobin variants, mutation of the enzyme biphosphoglycerate mutase (BPGM), or defects in components of the oxygen-sensing pathway. Hereditary thrombocytosis was first linked to mutations in genes encoding thrombopoietin (THPO) or the thrombopoietin receptor, MPL. More recently, germline mutations in JAK2, distinct from JAK2 V617F, and mutation of the gelsolin gene, were uncovered in several pedigrees of hereditary thrombocytosis. Hereditary neutrophilia has been described in one family with an activating germline mutation in CSF3R. The mutational basis for most hereditary myeloproliferative disorders has yet to be identified.