Optimization of Enzyme Essays to Enhance Reliability of Activity Measurements in Leukocyte Lysates for the Diagnosis of Metachromatic Leukodystrophy and Gangliosidoses.

(1) Lysosomal storage diseases are rare inherited disorders with no standardized or commercially available tests for biochemical diagnosis. We present factors influencing the quality of enzyme assays for metachromatic leukodystrophy (MLD) and gangliosidoses (GM1; GM2 variants B and 0) and validate the reliability and stability of testing in a retrospective analysis of 725 samples. (2) Patient leukocytes were isolated from ethylene-diamine-tetra-acetic acid (EDTA) blood and separated for subpopulation experiments using density gradient centrifugation or magnetic cell separation. Enzyme activities in whole leukocyte lysate and leukocyte subpopulations were determined. (3) The enzyme activities in leukocyte subpopulations differed significantly. Compared to lymphocytes, the respective enzyme activities were 2.31-4.57-fold higher in monocytes and 1.64-2.81-fold higher in granulocytes. During sample preparation, a considerable amount of the lysosomal enzymes was released from granulocytes. Nevertheless, with the sample preparation method used here, total leukocyte count proved to be more accurate than total protein amount as a reference unit for enzyme activities. Subsequent analysis of 725 individuals showed clear discrimination of enzyme activities in patient samples (48 MLD; 21 gangliosidoses), with a sensitivity of 100% and specificity of 98-99%.

Flow Cytometric Quantification of Granulocytic Alkaline Phosphatase Activity in Unlysed Whole Blood.

Translational research has improved the diagnosis and follow-up of hematological diseases and malignancies. However, some classical diagnostics used for research and clinical practice that have remain practically unchanged for decades may be better addressed through advances in flow cytometry technology, whereby more precise measurements may be implemented in a straightforward manner. The current method for semiquantitative analysis of granulocytic alkaline phosphatase (GAP) activity is still based on observer-dependent color-intensity classification. Here, we describe a novel strategy for flow cytometric quantification of GAP activity in which staining and analytical flow cytometry facilitate the detection and quantification of subpopulations of leukocytes with different GAP activities. Our experiments demonstrate the potential of flow cytometry as a simple and highly sensitive approach for measuring GAP activity in unlysed whole blood. Notably, a comparison of flow cytometry and enzyme cytochemistry techniques showed that enzyme activity scores were not similar, indicating that results needs to be interpreted with caution, given that the enzyme-substrate binding affinities may differ, as well as the subjective evaluation of the intensity of the precipitated dye. © 2020 Wiley Periodicals LLC. Basic Protocol: Protocol preparation, sample acquisition, and gating strategy for flow cytometric identification of alkaline phosphatase activity in granulocytes from whole blood samples Support Protocol 1: Sample preparation for granulocyte alkaline phosphatase determination by flow cytometry using no-lyse no-wash methods Support Protocol 2: Data analysis and formula to calculate the GAP score.

Inducible expression of a disease-associated ELANE mutation impairs granulocytic differentiation, without eliciting an unfolded protein response.

Severe congenital neutropenia (SCN) is characterized by a near absence of neutrophils, rendering individuals with this disorder vulnerable to recurrent life-threatening infections. The majority of SCN cases arise because of germline mutations in the gene elastase, neutrophil-expressed (ELANE) encoding the neutrophil granule serine protease neutrophil elastase. Treatment with a high dose of granulocyte colony-stimulating factor increases neutrophil production and reduces infection risk. How ELANE mutations produce SCN remains unknown. The currently proposed mechanism is that ELANE mutations promote protein misfolding, resulting in endoplasmic reticulum stress and activation of the unfolded protein response (UPR), triggering death of neutrophil precursors and resulting in neutropenia. Here we studied the ELANE mutation p.G185R, often associated with greater clinical severity (e.g. decreased responsiveness to granulocyte colony-stimulating factor and increased leukemogenesis). Using an inducible expression system, we observed that this ELANE mutation diminishes enzymatic activity and granulocytic differentiation without significantly affecting cell proliferation, cell death, or UPR induction in murine myeloblast 32D and human promyelocytic NB4 cells. Impaired differentiation was associated with decreased expression of genes encoding critical hematopoietic transcription factors (Gfi1, Cebpd, Cebpe, and Spi1), cell surface proteins (Csf3r and Gr1), and neutrophil granule proteins (Mpo and Elane). Together, these findings challenge the currently prevailing model that SCN results from mutant ELANE, which triggers endoplasmic reticulum stress, UPR, and apoptosis.

Functional characteristics of circulating granulocytes in severe congenital neutropenia caused by ELANE mutations.

BACKGROUND: Neutrophils and eosinophils are multifunctional granulocytes derived from common myelocytic-committed progenitor cells. Severe congenital neutropenia 1 (SCN1) caused by ELANE mutations is a rare disease characterized by very low numbers of circulating neutrophils. Little is known about the functional characteristics of the SCN1 granulocytes, except that eosinophilia has been noticed in both bone marrow and peripheral blood. In this study, we profiled the number and function of granulocytes in patients suffering from SCN1. METHODS: Nine patients diagnosed with SCN1 were enrolled in this study and absolute counts of eosinophils and neutrophils from bone marrow aspirates and peripheral blood samples were analysed. In addition, Ficoll-Paque enriched granulocytes from patients and healthy controls were analysed for specific eosinophil and neutrophil markers using flow cytometry and for NADPH-oxidase activity-profile by chemiluminescence. RESULTS: Our data demonstrate a skewed granulocyte population in SCN1 patients dominated by eosinophils in both bone marrow and peripheral blood. The latter was detected only by blood smear examination, but not by automated blood analysers. Furthermore, we show that the SCN1 eosinophils exerted normal production of reactive oxygen species generated by the NADPH-oxidase, however the response was profoundly different from that of healthy control neutrophils. CONCLUSIONS: SCN1 patients with ELANE mutations suffer from neutropenia yet display eosinophilia in the bone marrow and blood, as revealed by smear examination but not by automatic blood analysers. The SCN1 eosinophils are functionally normal regarding production of reactive oxygen species (ROS). However, the ROS profile produced by eosinophils differs drastically from that of neutrophils isolated from the same blood donor, implying that the eosinophilia in SCN1 cannot compensate for the loss of neutrophils regarding ROS-mediated functions.

CgAATase with specific expression pattern can be used as a potential surface marker for oyster granulocytes.

Granulocytes are known as the main immunocompetent hemocytes that play important roles in the immune defense of oyster Crassostrea gigas. In the present study, an alcohol acyltransferase (designed as CgAATase) with specific expression pattern was identified from oyster C. gigas, and it could be employed as a potential marker for the isolation of oyster granulocytes. The open reading frame (ORF) of CgAATase was of 1431 bp, encoding a peptide of 476 amino acids with a typically conserved AATase domain. The mRNA transcripts of CgAATase were highest expressed in hemocytes, lower expressed in hepatopancreas, mantle, gonad, gill, ganglion, adductor muscle, and labial palp. The mRNA expression level of CgAATase in hemocytes was significantly up-regulated at 3-12 h and reached the highest level (27.40-fold compared to control group, p < 0.05) at 6 h after Vibrio splendidus stimulation. The total hemocytes were sorted as granulocytes, semi-granulocytes and agranulocytes by Percoll® density gradient centrifugation. CgAATase transcripts were dominantly observed in granulocytes, which was 8.26-fold (p < 0.05) and 2.80-fold (p < 0.05) of that in agranulocytes and semi-granulocytes, respectively. The monoclonal antibody against CgAATase was produced and employed for the isolation of granulocytes with the immunomagnetic bead. CgAATase protein was mainly detected on the cytomembrane of granulocytes. About 85.7 ±â€¯4.60% of the granulocytes were positive for CgAATase and they could be successfully separated by flow cytometry with immunomagnetic bead coated with anti-CgAATase monoclonal antibody, and 97.7 ±â€¯1.01% of the rest hemocytes (agranulocytes and semi-granulocytes) were negative for CgAATase. The isolated primary granulocytes could maintain cell activity for more than one week in vitro culture that exhibited numerous filopodia. These results collectively suggested that CgAATase was a potential marker of oyster granulocytes, and the granulocytes could be effectively isolated from total circulating hemocytes by immunomagnetic bead coated with the anti-CgAATase monoclonal antibody.

Aldehyde dehydrogenase activity in cryopreserved cord blood cells for quality assessment prior to transplantation.

In umbilical cord blood transplantation (UCBT), the number of cluster of differentiation (CD)34+ cells and colony­forming units (CFUs) in the cord blood (CB) graft positively correlate with patient survival. Therefore, these parameters are currently used for quality assessment of the cryopreserved CB cells in the attached segment that is considered representative of the CB in the main bag prior to UCBT. Since aldehyde dehydrogenase (ALDH) activity is high in hematopoietic stem cells, the number of ALDH­bright (ALDHbr) cells was examined in comparison with the number of CD34+ cells and CFUs for the quality assessment of CB units. In the cryopreserved main bag, the number of ALDHbr cells in the CB unit exhibited positive correlation with the number of CD34+ cells, and with CFU­granulocytes/macrophages and total CFU counts. Furthermore, the concentration of ALDHbr cells in the cryopreserved attached segment was not significantly different compared to that of the main bag, suggesting that the attached segment is representative of the main bag. In conclusion, the present study suggested that ALDHbr cell counts in the cryopreserved attached segments may serve as a quality assessment indicator for CB units prior to UCBT.

N-demethylation of N-methyl-4-aminoantipyrine, the main metabolite of metamizole.

Metamizole is an old analgesic used frequently in some countries. Active metabolites of metamizole are the non-enzymatically generated N-methyl-4-aminoantipyrine (4-MAA) and its demethylation product 4-aminoantipyrine (4-AA). Previous studies suggested that 4-MAA demethylation can be performed by hepatic cytochrome P450 (CYP) 3A4, but the possible contribution of other CYPs remains unclear. Using human liver microsomes (HLM), liver homogenate and HepaRG cells, we could confirm 4-MAA demethylation by CYPs. Based on CYP induction (HepaRG cells) and CYP inhibition (HLM) we could identify CYP2B6, 2C8, 2C9 and 3A4 as major contributors to 4-MAA demethylation. The 4-MAA demethylation rate by HLM was 280 pmol/mg protein/h, too low to account for in vivo 4-MAA demethylation in humans. Since peroxidases can perform N-demethylation, we investigated horseradish peroxidase and human myeloperoxidase (MPO). Horse radish peroxidase efficiently demethylated 4-MAA, depending on the hydrogen peroxide concentration. This was also true for MPO; this reaction was saturable with a Km of 22.5 µM and a maximal velocity of 14 nmol/min/mg protein. Calculation of the entire body MPO capacity revealed that the demethylation capacity by granulocyte/granulocyte precursors was approximately 600 times higher than the liver capacity and could account for 4-MAA demethylation in humans. 4-MAA demethylation could also be demonstrated in MPO-expressing granulocyte precursor cells (HL-60). In conclusion, 4-MAA can be demethylated in the liver by several CYPs, but hepatic metabolism cannot fully explain 4-MAA demethylation in humans. The current study suggests that the major part of 4-MAA is demethylated by circulating granulocytes and granulocyte precursors in bone marrow.

The regulatory role of Dipeptidyl peptidase I on the activation of immune granulocytes.

Dipeptidyl peptidase I (DPPI), a lysosomal cysteine protease, required for activation of serine proteases of granulocytes including mast cells (MCs), neutrophils (NPs) and others, which were found in synovial tissue of patients with rheumatoid arthritis (RA). But, the role of DPPI associated with those cells in RA development is unclear. In this study, the collagen-induced-arthritis (CIA) rat-model was employed to investigate the expression and activity levels of DPPI and its association with RA progress. Primary granulocytes were freshly extracted from bone-marrows of normal or CIA rats, human mast cell line LAD-2 and primary neutrophils, human-recombinant-DPPI, DPPI-inhibitor Gly-Phe-CHN2 , LTB4, anti-IgE antibody, calcium ionophore were used to study the regulatory role of DPPI in cell activations. The increased DPPI activities in synovial fluids, serum, and bone-marrow homogenates of CIA rats associated with RA severities progress were observed after injections. MMP2/9 expressions in SFs and bone-marrow were in different patterns. Regular-Blood-Tests have shown the high leveled DPPI activities associated with granulocytes differentiations in-vivo in blood of CIA rats. In-vitro cell models, DPPI up-regulated the proliferation of primary bone-marrow granulocytes of normal rats, but inhibited that of CIA rats. DPPI up-regulated and Gly-Phe-CHN2 down-regulated MCs intracellular DPPI and chymase activities. Gly-Phe-CHN2 also inhibited the LTB4 -activated-NPs and NP-elastase activities. Following stimulation of calcium ionophore, the net-releases of DPPI and ß-hexosaminidase from MCs were increased over a time-course, while Gly-Phe-CHN2 down-regulated MCs and NPs activation. Our findings demonstrate the role of DPPI in regulating MCs and NPs activation, and modulating proteolysis in the process of RA.

Gingival Inflammation and Salivary or Serum Granulocyte-Secreted Enzymes in Patients With Polycystic Ovary Syndrome.

BACKGROUND: The objective of this cross-sectional study is to investigate levels of salivary and serum matrix metalloproteinase (MMP)-9, myeloperoxidase (MPO), neutrophil elastase (NE), and MMP-9/tissue inhibitor of MMP-1 (TIMP)-1 ratio in patients with polycystic ovary syndrome (PCOS) and systemically healthy controls in the presence or absence of gingivitis. METHODS: Serum and salivary levels of these biomarkers were evaluated in the following: 1) periodontally healthy women with PCOS (n = 45); 2) women with PCOS and gingivitis (n = 35); 3) systemically and periodontally healthy women (n = 25); and 4) systemically healthy women with gingivitis (n = 20). Enzyme-linked immunosorbent assay was used to determine levels of these biomarkers. A full-mouth clinical periodontal evaluation was performed for each patient. RESULTS: Salivary MMP-9 and NE levels, as well as MMP-9/TIMP-1 ratios, were higher in the systemically healthy women with gingivitis compared with periodontally healthy women with PCOS (P <0.001; P <0.01; and P <0.0001, respectively). Serum MMP-9 and MPO levels were higher in women with PCOS and gingivitis compared with periodontally healthy women with PCOS (P <0.05). Serum MMP-9 levels were lower in healthy women with gingivitis than systemically and periodontally healthy women or women with PCOS and gingivitis (P <0.05). PCOS groups exhibited a positive correlation among clinical periodontal parameters and serum MMP-9 levels or salivary MPO, NE levels, and MMP-9/MMP-1 ratio. Correlation was negative among clinical periodontal parameters and serum MMP-9 levels and MMP-9/TIMP-1 ratio in systemically healthy patients (P <0.05). CONCLUSIONS: The present findings emphasize that PCOS and gingival inflammation are associated with each other, as evidenced by salivary and serum levels of neutrophilic enzymes. This interaction may contribute to the perturbation of ovarian remodeling in PCOS.

Increased Granulocyte Heparanase Activity in Neutrophils from Patients with Lupus Nephritis and Idiopathic Membranous Nephropathy.

Heparanase is a ß-glucuronidase that cleaves sugar chains of heparan sulfate proteoglycans. It is believed that heparanase may be involved in the pathogenesis of proteinuria. The aim of this study was to assess the significance of heparanase in the pathogenesis of particular glomerulonephritis types. The evaluation of heparanase activity in serum, urine, and granulocytes and superoxide dismutase (SOD) activity in granulocytes of patients with lupus nephritis (n = 17), membranous nephropathy (n = 11), IgA nephropathy (n = 12), focal and segmental glomerulosclerosis (n = 18), mesangiocapillary glomerulonephritis (n = 12) and in 19 healthy volunteers were performed. The heparanase activity in granulocytes of patients with lupus nephritis and membranous nephropathy was higher than heparanase activity in granulocytes in the control group (p = 0.02 in both cases). This is the first observation of this phenomenon. There was no difference between SOD activity in granulocytes of patients with all assessed types of glomerulonephritis and the control group. A positive correlation between heparanase activity in urine and double-strain DNA antibodies (r = 0.51; p = 0.04), and reverse correlations between heparanase in urine and hemolytic activity of the complement (r = -0.57; p = 0.03) in the lupus nephritis group, and between heparanase activity in granulocytes and serum total protein level (r = -0.69; p = 0.02) in membranous nephropathy were observed. Increase in heparanase activity without changes in superoxide dismutase activity in the granulocytes from patients with lupus nephritis and membranous nephropathy was observed. It may be used as one of the markers of these disease activities.

Granulocytes in coronary thrombus evolution after myocardial infarction--time-dependent changes in expression of matrix metalloproteinases.

BACKGROUND: Remodeling of extracellular matrix is a key process during wound healing, which is strictly regulated by matrix metalloproteinases (MMPs) and their tissue inhibitors [tissue inhibitors of metalloproteinases (TIMPs)]. In this study, we evaluated intrathrombotic MMPs and TIMPs and their cellular origin during thrombus evolution after disruption of coronary atherosclerotic plaque. MATERIALS AND METHODS: Thrombectomy materials (N=120) obtained from patients with acute myocardial infarction were histologically classified in three groups based on thrombus age: fresh (<1day), lytic (1-5days), or organized (>5days) thrombi; materials showing a heterogeneous composition were classified according to oldest part. Presence and cellular origin of MMPs (MMP-1, MMP-2, MMP-8, MMP-9, and MMP-14) and TIMPs (TIMP-1, TIMP-2, and TIMP-3) was evaluated with immunostains (double) and with polymerase chain reaction. RESULTS AND CONCLUSION: MMPs and TIMPs were present in all the thrombectomy samples. A distinct temporal change in extent and cellular origin of MMPs and TIMPs during thrombus evolution was observed. In the early (fresh and lytic) stages of thrombus, high numbers of neutrophilic granulocytes occupy the thrombus mass and produce large amounts of MMPs and TIMPs. However, with progression of thrombus evolution (organizing stage) and diminishment of neutrophil granulocytes, there is disappearance of MMP-8 and MMP-9, steep decline of MMP-1 and TIMP-2, and progressive decrease of TIMP-3. In contrast, intrathrombotic MMP-2 and MMP-14 are present at a constant high level during the entire process of thrombus evolution. These temporal changes indicate a complex time-dependent function of MMPs, which are largely granulocyte derived, in the healing process of thrombus after plaque disruption.

New IDH1 mutant inhibitors for treatment of acute myeloid leukemia.

Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are driver mutations in acute myeloid leukemia (AML) and other cancers. We report the development of new allosteric inhibitors of mutant IDH1. Crystallographic and biochemical results demonstrated that compounds of this chemical series bind to an allosteric site and lock the enzyme in a catalytically inactive conformation, thereby enabling inhibition of different clinically relevant IDH1 mutants. Treatment of IDH1 mutant primary AML cells uniformly led to a decrease in intracellular 2-HG, abrogation of the myeloid differentiation block and induction of granulocytic differentiation at the level of leukemic blasts and more immature stem-like cells, in vitro and in vivo. Molecularly, treatment with the inhibitors led to a reversal of the DNA cytosine hypermethylation patterns caused by mutant IDH1 in the cells of individuals with AML. Our study provides proof of concept for the molecular and biological activity of novel allosteric inhibitors for targeting different mutant forms of IDH1 in leukemia.

The Involvement of Hemocyte Prophenoloxidase in the Shell-Hardening Process of the Blue Crab, Callinectes sapidus.

Cuticular structures of arthropods undergo dramatic molt-related changes from being soft to becoming hard. The shell-hardening process of decapod crustaceans includes sclerotization and mineralization. Hemocyte PPO plays a central role in melanization and sclerotization particularly in wound healing in crustaceans. However, little is known about its role in the crustacean initial shell-hardening process. The earlier findings of the aggregation of heavily granulated hemocytes beneath the hypodermis during ecdysis imply that the hemocytes may be involved in the shell-hardening process. In order to determine if hemocytes and hemocyte PPO have a role in the shell-hardening of crustaceans, a knockdown study using specific CasPPO-hemo-dsRNA was carried out with juvenile blue crabs, Callinectes sapidus. Multiple injections of CasPPO-hemo-dsRNA reduce specifically the levels of CasPPO-hemo expression by 57% and PO activity by 54% in hemocyte lysate at the postmolt, while they have no effect on the total hemocyte numbers. Immunocytochemistry and flow cytometry analysis using a specific antiserum generated against CasPPO show granulocytes, semigranulocytes and hyaline cells as the cellular sources for PPO at the postmolt. Interestingly, the type of hemocytes, as the cellular sources of PPO, varies by molt stage. The granulocytes always contain PPO throughout the molt cycle. However, semigranulocytes and hyaline cells become CasPPO immune-positive only at early premolt and postmolt, indicating that PPO expression in these cells may be involved in the shell-hardening process of C. sapidus.

Acquired factor VII deficiency associated with acute myeloid leukemia.

Isolated acquired factor VII deficiency is a rare coagulopathy. It has been reported in 31 patients with malignancy, sepsis, postoperatively, aplastic anemia, and during bone marrow transplantation. We discuss, through a new case of acquired factor VII deficiency, the characteristics of this disease when it is associated with acute myeloid leukemia. Acquired factor VII deficiency in hematological diseases can be caused by intensive chemotherapy, infections, or hepatic dysfunction. The best treatment in developing countries remains corticosteroids associated with plasma exchange, frozen plasma, and antibiotics.

Arginase I levels are decreased in the plasma of pediatric patients with atopic dermatitis.

BACKGROUND: Serum arginase levels have been shown to be elevated in conditions, such as trauma, cancer, chronic wounds, pregnancy, and diabetes. This also has been found to be true in atopic diseases, such as asthma and allergic rhinitis. OBJECTIVE: To study arginase activity in patients with atopic dermatitis (AD). METHODS: In this pilot study, arginase activity levels in 15 pediatric patients with AD were compared with those in controls to determine whether arginase levels in AD are altered as in patients with other atopic diseases. RESULTS: In contrast to the other diseases studied, arginase activity was found to be decreased in granulocytes and in the plasma of patients with AD compared with controls. This finding was coupled with a trend toward higher L-arginine plasma levels. CONCLUSION: In AD, a different mechanism of arginine metabolism seems to be stimulated, leading to the formation of nitric oxide pathway components causing suppression of the arginase pathway and impairment in skin hydration, collagen synthesis, and wound healing.

Increased oxidative stress response in granulocytes from older patients with a hip fracture may account for slow regeneration.

Proximal femur fracture, a typical fracture of the elderly, is often associated with morbidity, reduced quality of life, impaired physical function and increased mortality. There exists evidence that responses of the hematopoietic microenvironment to fractures change with age. Therefore, we investigated oxidative stress markers and oxidative stress-related MAPK activation in granulocytes from the young and the elderly with and without fractured long bones. Lipid peroxidation levels were increased in the elderly controls and patients. Aged granulocytes were more sensitive towards oxidative stress induced damage than young granulocytes. This might be due to the basally increased expression of SOD-1 in the elderly, which was not further induced by fractures, as observed in young patients. This might be caused by an altered MAPK activation. In aged granulocytes basal p38 and JNK activities were increased and basal ERK1/2 activity was decreased. Following fracture, JNK activity decreased, while ERK1/2 and p38 activities increased in both age groups. Control experiments with HL60 cells revealed that the observed p38 activation depends strongly on age. Summarizing, we observed age-dependent changes in the oxidative stress response system of granulocytes after fractures, for example, altered MAPK activation and SOD-1 expression. This makes aged granulocytes vulnerable to the stress stimuli of the fracture and following surgery.

Expression of transketolase-like gene 1 (TKTL1) depends on disease phase in patients with chronic myeloid leukaemia (CML).

PURPOSE: Overexpression of transketolase-like gene 1 (TKTL1) on RNA and protein level has been linked to tumour progression, metastasis and unfavourable patient outcome in many solid tumours. Chronic myeloid leukaemia (CML) cells show metabolic characteristics resembling deviations observed in TKTL1 overexpressing solid tumour cells. We therefore sought to evaluate TKTL1 gene expression in different phases of CML. METHODS: A total of 120 peripheral blood samples from 69 patients in various phases of CML and 21 healthy individuals were investigated. TKTL1 expression levels were determined by real-time quantitative polymerase chain reaction using LightCycler technology and normalised against beta-glucuronidase expression. RESULTS: A significantly lower TKTL1 expression was found in chronic phase (CP) CML patients compared to healthy controls. Lowest expression levels were observed in patients during blast crisis (BC). Baseline TKTL1 expression in CP patients did not have value in prognostication of subsequent favourable or dismal outcome. Further, more mature granulocytes showed significantly higher TKTL1 expression compared to immature CD34+ and CD34-/CD33+ cells both in healthy controls and in CML patients. CONCLUSION: TKTL1 expression levels appear to decline in the course of CML with lowest levels during BC. A potential reason is a shift of TKTL1-high-expressing mature granulocytes towards TKTL1-low-expressing immature cells and blasts.

The role of sterol-C4-methyl oxidase in epidermal biology.

Deficiency of sterol C4 methyl oxidase, encoded by the SC4MOL gene, has recently been described in four patients from three different families. All of the patients presented with microcephaly, congenital cataracts, and growth delay in infancy. The first patient has suffered since the age of six years from severe, diffuse, psoriasiform dermatitis, sparing only her palms. She is now 20 years old. The second patient is a 5 year old girl who has just started to develop dry skin and hair changes. The third and fourth patients are a pair of affected siblings with a severe skin condition since infancy. Quantitative sterol analysis of plasma and skin scales from all four patients showed marked elevation of 4α-methyl- and 4, 4'-dimethylsterols, consistent with a deficiency in the first step of sterol C4 demethylation in cholesterol biosynthesis. Mutations in the SC4MOL have been identified in all of the patients. SC4MOL deficiency is the first autosomal recessive disorder identified in the sterol demethylation complex. Cellular studies with patient-derived fibroblasts have shown a higher mitotic rate than control cells in cholesterol-depleted medium, with increased de novo cholesterol biosynthesis and accumulation of methylsterols. Immunologic analyses of granulocytes and B cells from patients and obligate carriers in the patients' families indicated dysregulation of immune-related receptors. Inhibition of sterol C4 methyl oxidase in human transformed lymphoblasts induced activation of the cell cycle. Additional studies also demonstrated diminished EGFR signaling and disrupted vesicular trafficking in cells from the affected patients. These findings suggest that methylsterols play an important role in epidermal biology by their influence on cell proliferation, intracellular signaling, vesicular trafficking and immune response. SC4MOL is situated within the psoriasis susceptibility locus PSORS9, and may be a genetic risk factor for common skin conditions. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias.

Nano-sized and micro-sized polystyrene particles affect phagocyte function.

Adverse effect of nanoparticles may include impairment of phagocyte function. To identify the effect of nanoparticle size on uptake, cytotoxicity, chemotaxis, cytokine secretion, phagocytosis, oxidative burst, nitric oxide production and myeloperoxidase release, leukocytes isolated from human peripheral blood, monocytes and macrophages were studied. Carboxyl polystyrene (CPS) particles in sizes between 20 and 1,000 nm served as model particles. Twenty nanometers CPS particles were taken up passively, while larger CPS particles entered cells actively and passively. Twenty nanometers CPS were cytotoxic to all phagocytes, ≥500 nm CPS particles only to macrophages. Twenty nanometers CPS particles stimulated IL-8 secretion in human monocytes and induced oxidative burst in monocytes. Five hundred nanometers and 1,000 nm CPS particles stimulated IL-6 and IL-8 secretion in monocytes and macrophages, chemotaxis towards a chemotactic stimulus of monocytes and phagocytosis of bacteria by macrophages and provoked an oxidative burst of granulocytes. At very high concentrations, CPS particles of 20 and 500 nm stimulated myeloperoxidase release of granulocytes and nitric oxide generation in macrophages. Cytotoxic effect could contribute to some of the observed effects. In the absence of cytotoxicity, 500 and 1,000 nm CPS particles appear to influence phagocyte function to a greater extent than particles in other sizes.

G protein-coupled receptor kinase-3-deficient mice exhibit WHIM syndrome features and attenuated inflammatory responses.

Chemokine receptor interactions coordinate leukocyte migration in inflammation. Chemokine receptors are GPCRs that when activated, are phosphorylated by GRKs to turn off G protein-mediated signaling yet recruit additional signaling machinery. Recently, GRK3 was identified as a negative regulator of CXCL12/CXCR4 signaling that is defective in human WHIM syndrome. Here, we report that GRK3-/- mice exhibit numerous features of human WHIM, such as impaired CXCL12-mediated desensitization, enhanced CXCR4 signaling to ERK activation, altered granulocyte migration, and a mild myelokathexis. Moreover, GRK3-/- protects mice from two acute models of inflammatory arthritis (K/BxN serum transfer and CAIA). In these granulocyte-dependent disease models, protection of GRK3-/- mice is mediated by retention of cells in the marrow, fewer circulating granulocytes in the peripheral blood, and reduced granulocytes in the joints during active inflammation. In contrast to WHIM, GRK3-/- mice have minimal hypogammaglobulinemia and a peripheral leukocytosis with increased lymphocytes and absent neutropenia. Thus, we conclude that the loss of GRK3-mediated regulation of CXCL12/CXCR4 signaling contributes to some, but not all, of the complete WHIM phenotype and that GRK3 inhibition may be beneficial in the treatment of inflammatory arthritis.