Superior leukocyte separation with a discontinuous one-step Ficoll-Hypaque gradient for the isolation of human neutrophils

Fusobacterium nucleatum dissemination by neutrophils

Recent studies uncovered that Fusobacterium nucleatum (Fn), a common, opportunistic bacterium in the oral cavity, is associated with a growing number of systemic diseases, ranging from colon cancer to Alzheimer's disease. However, the pathological mechanisms responsible for this association are still poorly understood. Here, we leverage recent technological advances to study the interactions between Fn and neutrophils. We show that Fn survives within human neutrophils after phagocytosis. Using in vitro microfluidic devices, we determine that human neutrophils can protect and transport Fn over large distances. Moreover, we validate these observations in vivo by showing that neutrophils disseminate Fn using a zebrafish model. Our data support the emerging hypothesis that bacterial dissemination by neutrophils is a mechanistic link between oral and systemic diseases. Furthermore, our results may ultimately lead to therapeutic approaches that target specific host-bacteria interactions, including the dissemination process.

Tumor suppressor p53 induces apoptosis of host lymphocytes experimentally infected by Leishmania major, by activation of Bax and caspase-3: a possible survival mechanism for the parasite

Apoptosis of infected host macrophages by Leishmania spp. is mainly addressed as one of the survival mechanisms of the parasite. However, there is no eligible data about whether tumor suppressor p53 could induce the apoptosis of host lymphocytes-treated Leishmania major via the mitochondrial intrinsic pathway. In this study, the amastigotes of L. major obtained from ten cutaneous leishmaniases (CL) patients were separately isolated and cultured in N.N.N and RPMI 1640 media. L. major was definitely confirmed by targeting Cyt b gene following sequencing. Subsequently, 2-3 × 10⁶ lymphocytes obtained from ten healthy individuals were isolated and co-cultured with 1-2 × 10⁶ L. major promastigotes. Following 6 h of exposure time, the enzymatic activity of caspase-3 was determined by fluorometric assay in each L. major-treated lymphocytes and cell control (only lymphocyte). The mRNA expressions of Bax, Bcl-2, p53, and caspase-3 genes were assessed by quantitative real-time-PCR analysis following 6 to 9 h of exposure times. The Bcl-2 mRNA expression in L. major-treated lymphocytes was 100-fold down-regulated relative to cell control. The mRNA expressions of p53 and caspase-3 were over-expressed 1.8- and 3.2-fold up-regulated relative to control lymphocytes, respectively. The Bax/Bcl-2 ratio and caspase-3 activity were higher than the control group (Pv <0.05). The current new findings indicate that the apoptotic effects of L. major-treated host lymphocytes dependent on p53 tumor suppressor via mitochondrial pathway may probably address as an auxiliary survival mechanism of L. major in CL patients. However, here is much work ahead to figure out the multiple functions played by apoptosis in the evasion of L. major.

Resolvin D1 protects periodontal ligament

Resolution agonists are endogenous mediators that drive inflammation to homeostasis. We earlier demonstrated in vivo activity of resolvins and lipoxins on regenerative periodontal wound healing. The goal of this study was to determine the impact of resolvin D1 (RvD1) on the function of human periodontal ligament (PDL) fibroblasts, which are critical for wound healing during regeneration of the soft and hard tissues around teeth. Primary cells were cultured from biopsies obtained from three individuals free of periodontal diseases. Peripheral blood mononuclear cells were isolated by density gradient centrifugation from whole blood of healthy volunteers. PGE2, leukotriene B4 (LTB4), and lipoxin A4 (LXA4) in culture supernatants were measured by ELISA. The direct impact of RvD1 on PDL fibroblast proliferation was measured and wound closure was analyzed in vitro using a fibroblast culture "scratch assay." PDL fibroblast function in response to RvD1 was further characterized by basic FGF production by ELISA. IL-1β and TNF-α enhanced the production of PGE2. Treatment of PDL cells and monocytes with 0.1-10 ng/ml RvD1 (0.27-27 M) reduced cytokine induced production of PGE2 and upregulated LXA4 production by both PDL cells and monocytes. RvD1 significantly enhanced PDL fibroblast proliferation and wound closure as well as basic FGF release. The results demonstrate that anti-inflammatory and proresolution actions of RvD1 with upregulation of arachidonic acid-derived endogenous resolution pathways (LXA4) and suggest resolution pathway synergy establishing a novel mechanism for the proresolution activity of the ω-3 docosahexaenoic acid-derived resolution agonist RvD1.

Differences in gene expression in lymphocytes of patients with high-tension, PEX, and normal-tension glaucoma and in healthy subjects

PURPOSE

Purpose Differences in the gene expression of leukocytes between patients with normal-tension glaucoma (NTG) and controls have been described. This study was performed in order to detect the differences in gene expression in peripheral lymphocytes in patients with primary open-angle glaucoma (POAG), patients with pseudoexfoliation glaucoma (PEX), and patients with NTG, and in healthy subjects.

METHODS

Ten patients with POAG, 11 patients with PEX, 10 patients with NTG, and 42 sex- and age-matched healthy persons were recruited. All study subjects were Caucasian. Twenty-two preselected genes were chosen and their expression in blood lymphocytes was quantified by real-time PCR. First, a univariate comparison among all groups was performed using the nonparametric Friedman test. Second, an L1 penalized logistic regression was performed.

RESULTS

Using the Friedman test to compare the 4 groups, 9 genes showed a different expression (p&lt;0.05). Comparing the controls vs patients with POAG, 8 genes were differently expressed (p&lt;0.05). Comparing patients with PEX vs controls, 9 genes were significantly different (p≤0.05). The statistical analysis of patients with NTG vs controls showed a difference in gene expression of 7 genes (p≤0.05). All these genes were upregulated in the glaucoma groups compared with the controls. The genes RhoGDI and RAR showed the most significant statistical difference in the L1-penalized logistic regression. The genes overexpressed in POAG/PEX differed from the ones in NTG.

CONCLUSIONS

In this masked study among the preselected 22 genes, several genes are overexpressed in the blood lymphocytes of Caucasian patients with glaucoma compared with the controls. The genes upregulated in POAG/PEX differed from the ones in NTG.

Blocking proinflammatory cytokine release modulates peripheral blood mononuclear cell response to Porphyromonas gingivalis

BACKGROUND

Chronic periodontitis (CP) is an inflammatory disease in which cytokines play a major role in the progression of disease. Anti-inflammatory cytokines (interleukin 4 [IL-4] and IL-10) were reported to be absent or reduced in diseased periodontal tissues, suggesting an imbalance between the proinflammatory and anti-inflammatory mediators. This study tests the hypothesis that there is cellular crosstalk mediated by proinflammatory and anti-inflammatory cytokines and that blocking proinflammatory cytokine (tumor necrosis factor-α [TNF-α] and IL-1) production will enhance anti-inflammatory cytokine (IL-4 and IL-10) production from peripheral blood mononuclear cells (PBMCs) in response to Porphyromonas gingivalis.

METHODS

PBMCs were isolated from individuals diagnosed with CP or healthy individuals and cultured for 24 hours. Concanavalin A (ConA) was used as an activator of lymphocyte function. Live and heat-killed P. gingivalis or lipopolysaccharide from P. gingivalis were used as the bacterial stimulants. TNF-α and IL-1 production was neutralized by specific antibodies against TNF-α and IL-1α or IL-β. Culture supernatants were evaluated by enzyme-linked immunosorbent assay for TNF-α, IL-1β, IL-4, and IL-10 production.

RESULTS

Live P. gingivalis did not result in any significant IL-10 or IL-4 release, whereas heat-killed P. gingivalis led to a significant increase in IL-10 levels compared with unstimulated or live P. gingivalis-stimulated cells from both healthy individuals or those with CP. Overall, PBMCs from patients with CP produced significantly lower IL-10 in response to ConA and P. gingivalis, suggesting chronic suppression of the anti-inflammatory cytokine production. Blocking the proinflammatory cytokine response did not result in any substantial change in IL-10 or IL-4 response to live P. gingivalis. Blocking the proinflammatory cytokine response restored IL-10 production by cells from CP in response to P. gingivalis lipopolysaccharide.

CONCLUSIONS

These findings suggest that PBMCs from patients with CP have suppressed anti-inflammatory cytokine production that can, in part, be restored by neutralizing proinflammatory cytokines. Monocytes are an important source of IL-10 production, and monocyte-derived IL-10 might play a regulatory role in the pathogenesis of CP.

Enamel matrix derivative promotes superoxide production and chemotaxis but reduces matrix metalloproteinase-8 expression by polymorphonuclear leukocytes

BACKGROUND

Polymorphonuclear leukocyte (PMN) is the predominant innate immune cell type activated in acute inflammation. The aim of this study is to determine the impact of enamel matrix derivative (EMD) on superoxide (O(2)(-)) generation, chemotaxis, and matrix metalloproteinase-8 (MMP-8) secretion by PMN in vitro to better understand the role of EMD in surgical wound healing.

METHODS

PMNs were isolated from healthy volunteers (n = 14). O(2)(-) generation was measured using a cytochrome c reduction assay. Chemotaxis was measured in a modified Boyden chamber. MMP-8 secretion was analyzed by Western blotting. A relative density method was used to determine the percentage of MMP-8 released from the PMNs in relation to the total cellular MMP-8 content.

RESULTS

O(2)(-) generation was significantly elevated when PMNs were stimulated with EMD (200 μg/mL) (P <0.01). Secondary stimulation of PMNs with 1 μM N-formyl-methionyl-leucyl-phenylalanine (fMLP) triggered earlier and more sustained O(2)(-) generation with EMD. EMD significantly increased PMN chemotactic activity (P <0.05). Combined stimulation with EMD plus fMLP resulted in significantly higher chemotaxis compared to fMLP alone (P <0.05). Conversely, EMD did not induce MMP-8 secretion from PMNs. MMP-8 secretion by PMNs in response to fMLP or serum-opsonized zymosan stimulation was significantly inhibited by EMD (P <0.05).

CONCLUSIONS

EMD has specific, differential actions on PMNs that suggest potential for enhancement of wound healing, bacterial and tissue debris clearance (O(2)(-) generation and chemotaxis), and suppression of tissue damage and degradation (MMP-8 ). Together, the data suggest that EMD enhances wound healing and reduces inflammation.

Ceruloplasmin induces polymorphonuclear leukocyte priming in localized aggressive periodontitis

BACKGROUND

Polymorphonuclear leukocytes (PMNs) from subjects with localized aggressive periodontitis (LAgP) present multiple functional abnormalities associated with a phenotypically primed PMN phenotype. Local inflammation is characterized by hypoxia, which leads to increased production of superoxide (O(2)(-)) by PMNs. Ceruloplasmin (CP) is also induced by hypoxia and inflammation. The aim of this study was to investigate the role of CP in O(2)(-) generation in PMNs from healthy subjects and patients with LAgP.

METHODS

PMNs were isolated from healthy subjects and those with LAgP (N = 36). Superoxide was measured by cytochrome-C reduction at 550 nm. Intracellular CP expression was analyzed by real-time polymerase chain reaction and Western blotting. Serum levels of CP were measured by enzyme-linked immunosorbent assay. Intracellular iron ion conversion was spectrophotometrically determined by measuring the absorbance of sigma-phenanthroline at 510 nm.

RESULTS

O(2)(-) generation was significantly higher in LAgP PMNs before and after stimulation with formyl-methionyl-leucyl-phenylalanine (100 nM). CP expression in PMNs and CP levels in serum were significantly higher in subjects with LAgP compared to the PMNs and serum samples from matched healthy donors (P <0.05). LAgP PMNs also had significantly higher levels of Fe(3+) and lower levels of Fe(2+) compared to healthy PMNs (P <0.05), suggesting increased iron conversion. Exogenous CP treatment of healthy PMNs resulted in significant increases in O(2)(-) generation and iron ion conversion similar to LAgP PMNs.

CONCLUSION

LAgP PMNs are primed to express higher levels of CP, leading to hypoxia-mediated O(2)(-) generation in PMNs and increased oxidative stress and neutrophil-mediated tissue injury in LAgP.

PDK1 regulates chemotaxis in human neutrophils

Phosphoinositide-dependent kinase (PDK1) plays a central role in signal transduction mediated by phosphatidylinositol 3-kinases (PI3K) and regulates cellular functions in neutrophils. Neutrophils from individuals diagnosed with localized aggressive periodontitis (LAP) present an in vivo phenotype with depressed chemotaxis. The aim of this study was to test the hypothesis that PDK1 regulates chemotaxis in neutrophils and is responsible for the abnormal neutrophil chemotaxis LAP. Neutrophil chemotaxis was significantly suppressed by the PDK1 inhibitor staurosporine. When cells were transfected with PDK1 siRNA, there was a significant reduction in chemotaxis, while superoxide generation was not significantly affected. In primary neutrophils from persons with LAP, PDK1 expression and activation levels were significantly reduced, and this reduction was associated with the reduced phosphorylation of Akt (Thr308) and chemotaxis. Analysis of these data demonstrates that PDK1 is essential for the chemotactic migration of neutrophils, and in the absence of PDK1, neutrophil chemotaxis is impaired.

Comparison of neutrophil functions in diabetic and healthy subjects with chronic generalized periodontitis

BACKGROUND

Diabetes mellitus is a systemic condition that has long been associated with an increased risk and severity of periodontal disease. Polymorphonuclear leukocytes (PMNs) play a key role in the maintenance of gingival and periodontal health. Reduced PMN function has been found in patients with diabetes.

AIM

The objective of this study was to evaluate PMN functions in 15 diabetic patients with chronic generalized periodontitis.

MATERIALS AND METHODS

Chemotaxis, superoxide production, phagocytosis and killing of Porphyromonas gingivalis by diabetic PMNs were evaluated relative to healthy and matched controls.

RESULTS

These analyses revealed a significant (P < 0.01) depression in the number of diabetic PMNs migrating along an fMLP gradient. In addition, a significant (P < 0.01) enhancement of diabetic PMN superoxide production was observed. Phagocytosis (P < 0.05) and killing by diabetic PMN of P. gingivalis was also impaired significantly (P < 0.01).

Polymorphonuclear leukocyte phagocytic function increases in plasminogen knockout mice

BACKGROUND

Mice lacking plasminogen (PG-/-) require alternative pathways of fibrinolysis for survival. This may depend on polymorphonuclear leukocytes (PMN) that can clear soluble and insoluble fibrin(ogen) through PG-independent processes. Our objective was to demonstrate that PMNs from PG-/- mice exhibit increased Mac-1 dependent phagocytic activity, which may explain their increased fibrin(ogen)lytic activity compared with wild type (PG+/+) mice.

METHODS

Phagocytic activity of PMNs from PG-/- and PG+/+ mice was compared following exposure to Staphylococcus aureus (S. aureus) particles and the expression of Mac-1 was assessed in parallel by flow cytometric analysis. Resistance to phorbol-12-myristate-13-acetate (PMA)-induced cell death was compared between PMNs from the different genotypes.

RESULTS

Stimulation of PG-/- PMNs by opsonized S. aureus diluted in PG-/- plasma significantly increased phagocytosis (15-fold) compared with stimulation of PG+/+ PMNs in PG+/+ plasma. Incubation of PG-/- PMNs with PG+/+ plasma (control) or PG-/- plasma supplemented with human PG inhibited this increased phagocytic activity. Mac-1 cell surface density increased 6.2+/-1.0-fold in PG-/- PMNs versus 2.9+/-0.6-fold in PG+/+ PMNs (P < 0.01) indicating that Mac-1 may be associated with increased phagocytic activity. Supporting this, treatment of PG-/- PMNs with an anti-Mac-1 antibody in PG-/- plasma inhibited phagocytic activity. In addition, physiologic PG blocked Mac-1 accessibility at the surface of PMNs. Addition of PMA resulted in 33% death of PMNs from PG-/- mice versus 68% in PG+/+ controls (P < 0.001).

CONCLUSIONS

PMNs from PG-/- mice exhibit a Mac-1 dependent increase in phagocytic activity that is suppressed with human PG, an anti-Mac-1 antibody or the plasma from PG+/+ mice. The propensity for PMNs from PG-/- mice to be activated in response to PMA together with their relative resistance to PMA-toxicity may contribute to increased PMN half-life and enhanced fibrin(ogen) clearance in the setting of PG deficiency.

Platelet-rich plasma: growth factors and pro- and anti-inflammatory properties

BACKGROUND

Platelet-rich plasma (PRP) promotes regeneration of bone, presumably through the action of concentrated growth factors. However, it is not clear how PRP affects the inflammatory response. The purpose of this study was to analyze the growth factors in PRP and to study the effects of PRP on monocyte cytokine release and lipoxin A(4) (LXA(4)) generation.

METHODS

PRP was prepared from healthy donors. Platelet-derived growth factor (PDGF)-AB, PDGF-BB, transforming growth factor-beta1, insulin-like growth factor-I, fibroblast growth factor-basic (FGF-b), epidermal growth factor (EGF), vascular endothelial growth factor, interleukin-12 (p40/70), and regulated on activation, normal T-cell expressed and secreted (RANTES) levels were evaluated by enzyme-linked immunosorbent assay and bead-based multiplexing. Peripheral blood monocytes were isolated and cultured with or without PRP. Cytokine, chemokine, and LXA(4) levels as well as monocyte chemotactic migration were analyzed.

RESULTS

Growth factors were increased significantly in PRP compared to whole blood (WB) and platelet-poor plasma. Monocyte chemotactic protein-1 (MCP-1) was suppressed significantly by PRP, whereas RANTES was increased significantly in monocyte cultures. LXA(4) levels were significantly higher in PRP compared to WB. PRP stimulated monocyte chemotaxis in a dose-dependent fashion, whereas RANTES, in part, was responsible for PRP-mediated monocyte migration.

CONCLUSIONS

PRP is a rich source of growth factors and promoted significant changes in monocyte-mediated proinflammatory cytokine/chemokine release. LXA(4) was increased in PRP, suggesting that PRP may suppress cytokine release, limit inflammation, and, thereby, promote tissue regeneration.

Interaction of non-adherent suspended neutrophils to complement opsonized pathogens: a new assay using optical traps

Phagocytosis of opsonized pathogens by circulating non-adherent neutrophils is an essential step in host defense, which when overwhelmed contributes to sepsis. To investigate the role played by ligation of complement receptors CR3 and CR4 in non-adherent neutrophils, we designed a novel assay system utilizing dual optical traps, respectively, holding a suspended unactivated cell and presenting a specific ligand-coated bead to the cell surface. We chose anti-CD18 as an example ligand, mimicking the bacterial opsonizing complement fragment iC3b. Presentation of anti-CD18-coated beads elicited both pseudopodial protrusion and subsequent phagocytosis. This is in sharp contrast to previously reported responses of adherent neutrophils, which phagocytize opsonized particles without pseudopod formation. We used this same new assay to probe actomyosin pathways in the neutrophil's pseudopodial and phagocytic response. Disruption of actin or inhibition of myosin light-chain kinase dose-dependently reduced pseudopod formation and phagocytosis rates. In summary, i) the new dual trap assay can be used to study the responses of suspended neutrophils to a variety of ligands, and ii) in a first application of this technique, we found that local ligation of CR3/4 in unactivated neutrophils in suspension induces pseudopod formation and phagocytosis at that site, and that these events occur via an actomyosin-dependent pathway.

RvE1 protects from local inflammation and osteoclast- mediated bone destruction in periodontitis

Periodontitis is a well-appreciated example of leukocyte-mediated bone loss and inflammation that has pathogenic features similar to those observed in other inflammatory diseases such as arthritis. Resolvins are a new family of bioactive products of omega-3 fatty acid transformation circuits initiated by aspirin treatment that counter proinflammatory signals. Because it is now increasingly apparent that local inflammation plays a critical role in many diseases, including cardiovascular disease, atherosclerosis, and asthma, experiments were undertaken to evaluate the actions of the newly described EPA-derived Resolvin E1 (RvE1) in regulation of neutrophil tissue destruction and resolution of inflammation. The actions of an aspirin-triggered lipoxin (LX) analog and RvE1 in a human disease, localized aggressive periodontitis (LAP), were determined. Results indicate that neutrophils from LAP are refractory to anti-inflammatory molecules of the LX series, whereas LAP neutrophils respond to RvE1. In addition, RvE1 specifically binds to human neutrophils at a site that is functionally distinct from the LX receptor. Consistent with these potent actions, topical application of RvE1 in rabbit periodontitis conferred dramatic protection against inflammation induced tissue and bone loss associated with periodontitis.

Effect of neutrophil apoptosis on monocytic cytokine response to Porphyromonas gingivalis lipopolysaccharide

BACKGROUND

Neutrophil apoptosis may play a critical role in the resolution of inflammation by stimulating anti-inflammatory cytokine generation from monocytes. In this study, we investigated the effect of apoptotic neutrophils on interleukin (IL)-10 and IL-1beta production from monocytes in response to Porphyromonas gingivalis lipopolysaccharide.

METHODS

Peripheral blood neutrophils from healthy individuals were isolated by sodium diatrizoate density gradient centrifugation. In order to induce apoptosis, neutrophils were cultured for 24 hours in modified Dulbecco's medium supplemented with 10% autologous serum. Cell apoptosis was quantified by Annexin V positivity and loss of CD16 expression on the cell surface. Peripheral blood mononuclear cells were isolated from the same subjects; monocytes were purified by magnetic cell sorting and cultured with or without apoptotic or fresh neutrophils. Lipopolysaccharide from Porphyromonas gingivalis was used for cell stimulation. IL-1beta and IL-10 levels in supernatants were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

IL-10 generation was significantly increased in monocytes cultured with apoptotic neutrophils compared to monocytes alone or cocultured with fresh neutrophils (P <0.05). IL-1beta was suppressed both in resting and lipopolysaccharide-stimulated monocytes in the presence of apoptotic neutrophils compared to monocytes alone or monocytes cultured with fresh neutrophils at all time points (P <0.05).

CONCLUSION

Neutrophil apoptosis provides a signal to monocytes, changing the phenotype of the monocyte resulting in the production of anti-inflammatory cytokines and suppression of proinflammatory cytokines in response to lipopolysaccharide.

Enhanced superoxide release and elevated protein kinase C activity in neutrophils from diabetic patients: association with periodontitis

Inflammation and oxidative stress are important factors in the pathogenesis of diabetes and contribute to the pathogenesis of diabetic complications. Periodontitis is an inflammatory disease that is characterized by increased oxidative stress, and the risk for periodontitis is increased significantly in diabetic subjects. In this study, we examined the superoxide (O(2)(-))-generating reduced nicotinamide adenine dinucleotide phosphate-oxidase complex and protein kinase C (PKC) activity in neutrophils. Fifty diabetic patients were grouped according to glycemic control and the severity of periodontitis. Neutrophils from diabetic patients with moderate [amount of glycated hemoglobin (HbA(1c)) between 7.0% and 8.0%] or poor (HbA(1c) >8.0%) glycemic control released significantly more O(2)(-) than neutrophils from diabetic patients with good glycemic control (HbA(1c) <7.0%) and neutrophils from nondiabetic, healthy individuals upon stimulation with 4beta-phorbol 12-myristate 13-acetate or N-formyl-Met-Leu-Phe. Depending on glycemic status, neutrophils from these patients also exhibited increased activity of the soluble- and membrane-bound forms of PKC, elevated amounts of diglyceride, and enhanced phosphorylation of p47-phox during cell stimulation. In addition, we report a significant correlation between glycemic control (HbA(1c) levels) and the severity of periodontitis in diabetic patients, suggesting that enhanced oxidative stress and increased inflammation exacerbate both diseases. Thus, hyperglycemia can lead to a novel form of neutrophil priming, where elevated PKC activity results in increased phosphorylation of p47-phox and O(2)(-) release.

Differentiation of HL-60 cells to granulocytes involves regulation of select diacylglycerol kinases (DGKs)

Diacylglycerol Kinases (DGKs) are a family of enzymes that regulate the levels of different pools of diacylglycerol (DAG), affecting DAG-mediated signal transduction. Since DAG is known to play several important regulatory roles in granulocyte physiology, we investigated the expression pattern of DGK isoforms throughout differentiation of HL-60 cells to granulocytes. HL-60 cells were incubated with 1.25% dimethyl-sulfoxide (DMSO) to initiate differentiation and total RNA isolated at different time points. DGK expression was assessed through Northern blot, end-point PCR, and real-time PCR. The non-selective inhibitors R59022 and R59949 were used to block DGK at different time points throughout differentiation. CD11b and GPI-80, reactive oxygen species (ROS) generation, changes in the cell cycle, and apoptosis were used as markers of differentiation. Of the nine isoforms of DGK evaluated (alpha, delta, epsilon, gamma, zeta, beta, theta;, iota, eta), only five (alpha, delta, epsilon, gamma, and zeta) were expressed in HL-60 cells. DGKalpha was virtually absent in non-differentiated cells, but was markedly upregulated throughout differentiation. The other isoforms (delta, epsilon, gamma, and zeta) were expressed in undifferentiated HL-60 cells but were substantially decreased throughout differentiation. Non-selective blocking of DGK with R59022 and R59949 led to acceleration of differentiation, reducing the time necessary to observe upregulation of CD11b, GPI-80 and generation of ROS by 50%. Likewise, the cell cycle was disrupted when DGK isoforms were inhibited. These results provide evidence that DGK levels are dynamically regulated throughout differentiation and that expression of DGKs play an important regulatory function during the differentiation of neutrophils.

Hereditary gingival fibromatosis associated with generalized aggressive periodontitis: a case report

BACKGROUND

Hereditary gingival fibromatosis is a rare, genetically inherited overgrowth condition that is clinically characterized by a benign fibrous enlargement of maxillary and mandibular keratinized gingiva. A syndromic association between gingival fibromatosis and a wide variety of other genetically inherited disorders has been described. However, its coexistence with aggressive periodontitis has not been reported.

METHODS

A 24-year-old African-American female, patient (proband X, [Px]) reported with a chief complaint of tooth mobility and gingival enlargement. Clinical examination revealed moderate to severe gingival overgrowth on both mandible and maxilla. Generalized attachment loss and mobility of the teeth were observed. Radiographic evaluation demonstrated severe alveolar bone loss. The patient was diagnosed with gingival fibromatosis and aggressive periodontitis based on the clinical and radiographic findings. Her brother (Bx) and her mother (Mx) were evaluated and diagnosed with gingival fibromatosis suggesting that this is a dominant trait in the family and gingival fibromatosis might be of hereditary origin. In addition, the brother also exhibited localized aggressive periodontitis. Medical history revealed no other systemic or local contributory factors associated with the oral findings in any of the subjects.

RESULTS

Surgical therapy included internal bevel gingivectomy combined with open flap debridement procedures for Px and Bx. Only internal bevel gingivectomy was performed for Mx since there was mild bone resorption and no intrabony defects. At the time of surgery, gingival biopsies were obtained and fixed in 4% paraformaldehyde. Multiple serial sections were stained with hematoxylin and eosin. Microscopic evaluation of the gingival specimens revealed large parallel collagen bundles associated with scarce fibroblasts in the connective tissue. The collagen bundles reached into the subepithelial connective tissue where elongated rete-pegs were also observed. Following the completion of the treatment, no signs of recurrence or bone resorption were observed over 2-year follow-up.

CONCLUSIONS

This is the first report of hereditary gingival fibromatosis associated with aggressive periodontitis. Combined treatment comprising removal of fibrotic gingival tissue and traditional flap surgery for the elimination of intrabony defects represents a unique treatment approach in periodontal therapy. Two-year follow-up revealed that both the gingival overgrowth and the destructive lesions were successfully treated.

Increased expression of matrix metalloproteinases in mononuclear blood cells of normal-tension glaucoma patients

PURPOSE

Glaucomatous optic neuropathy involves tissue remodeling by matrix metalloproteinases (MMPs). In this study we investigated MMP gene expression in circulating leukocytes isolated from normal tension glaucoma (NTG) patients in comparison to healthy controls.

METHODS

Blood samples were collected from 6 glaucoma patients and 6 age- and sex-matched healthy controls. Leukocytes were separated using Ficoll-Hypaque gradient. mRNA pools were used for subtractive hybridization to identify genes with altered expression. The subtracted genes were sequenced and individual mRNA pools were quantified using semiquantitative RT-PCRs. Target PCR products were confirmed using sequence-based restriction analysis. In this study we focused on MMPs.

RESULTS

MMP-9 and MT1-MMP (MMP-14) were subtracted as upregulated genes in the group of NTG patients. Upregulation of these genes was confirmed by RT-PCR and Western-blot analysis in all 6 patients. The expression of the tissue inhibitor of matrix metalloproteinases TIMP-1 was slightly enhanced in patients as compared with controls. Expression of MMP-2 was not detected in leukocytes either in glaucoma patients or in healthy subjects.

CONCLUSION

A simultaneous upregulation of both MMP-9 and MT1-MMP gene expression and only slightly enhanced expression of TIMP-1 suggest an increased enzymatic matrix metalloproteinase activity delivered by mononuclear blood cells in these patients.

Identification of mRNAs for the various diacylglycerol kinase isoforms in neutrophils from patients with localized aggressive periodontitis

BACKGROUND

Diacylglycerol kinase (DGK) metabolizes diacylglycerol (DAG), an endogenous activator of protein kinase C, to phosphatidic acid. We have previously reported increased DAG in neutrophils from patients with localized aggressive periodontitis (LAP) associated with reduced DGK activity. This reduction could be related to a mutation, post-translational modification, differential expression, or lack of expression of a particular isoform(s).

OBJECTIVE

The aim of this study was to identify the mRNAs for DGK isoforms in normal and LAP neutrophils.

METHODS

The alpha-, gamma-, and delta-isoforms of DGK were identified by polymerase chain reaction (PCR) using specific oligonucleotide primers for each isoform. The PCR products were isolated and sequenced for comparison to published sequences to confirm the validity of the PCR reaction. Total RNA was isolated from LAP and normal neutrophils, and northern blotting and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) was used to examine the level of mRNA for each isoform.

RESULTS

No major differences were found in the isoform pattern between resting normal and LAP neutrophils. However, the levels of mRNA for the alpha- and gamma-isoforms of DGK were increased in normal neutrophils while slightly decreased in LAP cells upon stimulation with N-formyl-methionyl-leucyl-phenylalanine (fMLP).

CONCLUSION

These data suggest that alterations in the mRNAs for the various isoforms of DGK during cell stimulation and the involvement of DGK that is expressed in multiple forms are subject to a variety of regulatory/control mechanisms and these mechanisms may explain the role of the 'primed' neutrophil phenotype associated with LAP.

Glutathione in gingival crevicular fluid and its relation to local antioxidant capacity in periodontal health and disease

AIMS

To determine possible changes in gingival crevicular fluid (GCF) antioxidant defence in chronic adult periodontal disease and to investigate the nature of the local radical scavenging mechanisms, with particular reference to glutathione.

METHODS

GCF and plasma were collected from patients with chronic periodontitis and age and sex matched control subjects (n = 10). Polymorphonuclear leucocytes (PMNLs) were prepared and gingival epithelial cells (GECs) were collected by conventional methods from periodontally healthy subjects. PMNL were stimulated with F-Met-Leu-Phe after cytochalasin B treatment. Enhanced chemiluminescence was used to determine the total antioxidant capacity and to investigate the activity of cell fractions and reducing agents. GCF concentrations of reduced (GSH) and oxidised (GSSG) glutathione were determined by high performance liquid chromatography.

RESULTS

Plasma and GCF from patients contained lower mean (SD) total antioxidant capacity (501.8 (123) micro M Teq/litre and 658.3 (392) micro M Teq/litre, respectively) compared with controls (577.9 (99.8) and 1351.5 (861) micro M Teq/litre, respectively). Antioxidant light recovery profiles for GCF demonstrated a stepped response, not seen in plasma, which was inhibited by N-ethylmaleimide. This response was also detected in the cytosolic fraction of GEC and anaerobically stimulated PMNL. Similar antioxidant profiles, inhibitable by N-ethylmaleimide, were obtained with cysteamine, cysteine, and GSH. Control GCF contained high mean (SD) concentrations of glutathione (GSH, 1899.8 (494.4) micro M; GSSG, 256.8 (152.4) micro M). GCF from patients with periodontitis contained significantly lower amounts of GSH (mean, 1183.1; SD, 580.3 micro M) and GSSG (mean, 150.1; SD, 44.9 micro M).

CONCLUSIONS

GSH values and total antioxidant capacity are reduced in chronic periodontal disease. The high concentrations of GSH present in GCF in health are similar to those found extracellularly in the lung and may represent an important antioxidant and anti-inflammatory defence strategy common to exposed epithelial surfaces.

Arginine-rich cationic polypeptides amplify lipopolysaccharide-induced monocyte activation

The human neutrophil-derived cationic protein CAP37, also known as azurocidin or heparin-binding protein, enhances the lipopolysaccharide (LPS)-induced release of tumor necrosis factor alpha (TNF-alpha) in isolated human monocytes. We measured the release of the proinflammatory cytokine interleukin-8 (IL-8) in human whole blood and found that in addition to CAP37, other arginine-rich cationic polypeptides, such as the small structurally related protamines, enhance LPS-induced monocyte activation. As CAP37 and protamines share high levels of arginine content, we tested different synthetic poly-L-amino acids and found that poly-L-arginine, and to a lesser extent poly-L-lysine, increased IL-8 production in LPS-stimulated human whole blood. Protamine-enhanced LPS responses remained unaffected by the presence of free L-arginine or L-lysine, indicating that basic polypeptides but not basic amino acids act synergistically with LPS. In agreement with observations previously reported for CAP37, the LPS-enhancing effect of poly-L-arginine was completely abolished upon antibody blockade of the human LPS receptor, CD14. Protamines, either immobilized or in solution, bound LPS specifically. Poly-L-arginines, protamines, and CAP37 were equally effective in inhibiting binding of LPS to immobilized L-arginines. Taken together, our results suggest a CD14-dependent mechanism by which arginine-rich cationic proteins modulate LPS-induced monocyte activation and support the prediction that other strongly basic proteins could act as amplifiers of LPS responses.

Inhibitory effect of synthetic histatin 5 on leukotoxin from Actinobacillus actinomycetemcomitans

Actinobacillus actinomycetemcomitans is a gram-negative bacterium strongly implicated in the pathogenesis of juvenile periodontitis. This periodontal pathogen synthesizes a leukotoxin that destroys human polymorphonuclear leukocytes (PMNs), and this toxin is thought to be responsible for the virulence of A. actinomycetemcomitans. It was therefore of interest to assess whether major virulence factors of periodontal pathogens were neutralized by salivary components. This study focuses on the effect of histatins, components of the nonimmune oral defense system, on leukotoxin activity. Leukotoxin was extracted with polymyxin B from freshly grown anaerobic cultures of A. actinomycetemcomitans strain Y4. PMNs isolated from blood of healthy human volunteers were incubated in a cytotoxicity assay containing PMNs (10(7) cells/ml) and leukotoxin preparation (0-500 microg/ml) in Hanks' balanced salt solution at 37 degrees C for 0-120 min with or without synthetic histatin 5 (0-500 microM). Cytotoxicity was measured by release of lactate dehydrogenase (LDH) at different time intervals. Histatin 5 neutralized the toxic effect of the leukotoxin preparation in a concentration-dependent manner, with an IC(50) value of 150 microM. When PMNs were preincubated with histatin 5 (300 microM), washed and subsequently exposed to leukotoxin, no protective effect was observed. This observation suggests a mechanism of inhibition whereby histatin 5 either directly neutralizes the leukotoxin or interferes with the leukotoxin-PMN interaction. The inhibitory effect of histatin 5 on leukotoxic activity may suggest a new biological function of histatins in the oral cavity as a naturally occurring secondary antibiotic.

Association of FcgammaRII with low-density detergent-resistant membranes is important for cross-linking-dependent initiation of the tyrosine phosphorylation pathway and superoxide generation

IgG immune complexes trigger humoral immune responses by cross-linking of FcRs for IgG (FcgammaRs). In the present study, we investigated role of lipid rafts, glycolipid- and cholesterol-rich membrane microdomains, in the FcgammaR-mediated responses. In retinoic acid-differentiated HL-60 cells, cross-linking of FcgammaRs resulted in a marked increase in the tyrosine phosphorylation of FcgammaRIIa, p58(lyn), and p120(c-cbl), which was inhibited by a specific inhibitor of Src family protein tyrosine kinases. After cross-linking, FcgammaRs and tyrosine-phosphorylated proteins including p120(c-cbl) were found in the low-density detergent-resistant membrane (DRM) fractions isolated by sucrose-density gradient ultracentrifugation. The association of FcgammaRs as well as p120(c-cbl) with DRMs did not depend on the tyrosine phosphorylation. When endogenous cholesterol was reduced with methyl-beta-cyclodextrin, the cross-linking did not induce the association of FcgammaRs as well as p120(c-cbl) with DRMs. In addition, although the physical association between FcgammaRIIa and p58(lyn) was not impaired, the cross-linking did not induce the tyrosine phosphorylation. In human neutrophils, superoxide generation induced by opsonized zymosan or chemoattractant fMLP was not affected or increased, respectively, after the methyl-beta-cyclodextrin treatment, but the superoxide generation induced by the insoluble immune complex via FcgammaRII was markedly reduced. Accordingly, we conclude that the cross-linking-dependent association of FcgammaRII to lipid rafts is important for the activation of FcgammaRII-associated Src family protein tyrosine kinases to initiate the tyrosine phosphorylation cascade leading to superoxide generation.

Altered gene expression in lymphocytes of patients with normal-tension glaucoma

BACKGROUND

In glaucoma there is a loss of retinal ganglion cells. There is evidence that this loss can occur by apoptosis. The signal transduction leading to retinal ganglion cell apoptosis in glaucoma is not yet clear. The present study compares the gene expression in lymphocytes of normal tension glaucoma patients (NTG-patients) with the one of healthy controls.

METHODS

Subtractive hybridization was used to compare mRNA in lymphocytes of six vasospastic NTG-patients with six age and sex matched healthy subjects.

RESULTS

Genes coding for p53-protein, NTP (neural thread protein) and 20 S proteasome subunit XAPC7 were overexpressed, whereas those coding for XPGC (Xeroderma pigmentosum gene), the survivin protein as well as one type of ABC transport protein were underexpressed.

CONCLUSION

In comparison to healthy controls, patients with vasospastic NTG seem to over- as well as under-express certain genes in their lymphocytes.

Glucose-6-phosphatase mutation G188R confers an atypical glycogen storage disease type 1b phenotype

Glycogen storage disease type 1a (GSD 1a) is caused by a deficiency in microsomal glucose-6-phosphatase (G6Pase). A variant (GSD 1b) is caused by a defect in the transport of glucose-6-phosphate (G6P) into the microsome and is associated with chronic neutropenia and neutrophil dysfunction. Mutually exclusive mutations in the G6Pase gene and the G6P transport gene establish GSD la and GSD 1b as independent molecular processes and are consistent with a multicomponent translocase catalytic model. A modified translocase/catalytic unit model based on biochemical data in a G6Pase knockout mouse has also been proposed for G6Pase catalysis. This model suggests coupling of G6Pase activity and G6P transport. A 5-mo-old girl with hypoglycemia, hepatomegaly, and lactic acidemia was diagnosed with GSD 1a. She also developed neutropenia, neutrophil dysfunction, and recurrent infections characteristic of GSD 1b. Homozygous G188R mutations of the G6Pase gene were identified, but no mutations in the G6P translocase gene were found. We have subsequently identified a sibling and two unrelated patients with similar genotypic/phenotypic characteristics. The unusual association of neutrophil abnormalities in patients with homozygous G188R mutations in the G6Pase gene supports a modified translocase/catalytic unit model.

Immunoglobulin Fc receptors in clinical strains of staphylococcus aureus do not confer resistance to phagocytosis in an in vitro assay

Staphylococcus aureus binds Immunoglobulin G (IgG) on its external surface due to the presence of specific receptors for the Fc domain of this immunoglobulin. This mechanism represents a kind of camouflage against phagocytic cells. In order to confirm that possibility an in vitro evaluation of the phagocytic activity of leukocytes polymorpho-nuclear (PMN) against strains of Staphylococcus aureus was done, comparing 18 strains isolated from clinical samples and 16 from healthy individuals. The presence of Fc receptors was evaluated by haemagglutination (HA) with erythrocytes group A after incubation of the strains with IgG anti blood group A. Phagocytosis of S. aureus was carried out by mixing live bacteria with a suspension of human PMN and incubating at 37 degrees C for 1 h; survivors were counted as colony forming units by plating. The strains from clinical specimens showed higher HA than those from healthy individuals (p = 0.01); but the former were killed more efficiently than the latter (80-90% and 40%, respectively). It is may be possible that S. aureus showed different behavior in vivo, where could express other virulence factors to prevent the action of phagocytes.

Morphology of human neutrophils: a comparison of cryofixation, routine gluteraldehyde fixation, and the effects of dimethyl sulfoxide

Cell shape and density are critical to the evaluation of neutrophil function and/or activation. Dimethyl sulfoxide-cryofixation-freeze-substitution processing (DCF) instantly preserves cell processes and ultrastructural elements with fewer artifacts than routine chemical fixation with glutaraldehyde and postfixation osmium tetroxide (GO). This study morphometrically examined density-separated neutrophils to assess differences in DCF and GO processing procedures and studied the effect of dimethyl sulfoxide followed by GO fixation (DGO) on morphology. Fifteen consecutive neutrophils were analyzed using computerized planimetry for differences in DCF v. GO treatments (n = 4) and DGO v. GO treatments (n = 4). Cryofixed and DGO-fixed cells were significantly rounder than GO cells which had a more irregular surface with membrane projections. The cell volume of GO cells was 27-30% smaller than in DCF or DGO processing, while the surface area was similar. The increased volume in DCF and DGO cells did not appear to be due to abnormal cell swelling, since membranes, nuclear envelope, and mitochondrial cristae were more intact than in GO cells. Preservation of mitochondria as well as endocytic caveolae with a subplasmalemmal coating was best in DCF samples, moderate in DGO, and poorest in GO. Morphometric data showed that the nuclear compartment was 22% smaller, while the cytoplasm (and its associated compartments) was 29% smaller in GO compared to DCF-processed neutrophils. This was consistent with the more dense cytoplasm in GO cells. Pretreatment of neutrophils with dimethyl sulfoxide (DMSO) resulted in volume preservation and improved the morphology of GO fixation. In summary, DCF appears to be an excellent method for preserving neutrophil membranes and cytoplasmic organelles (particularly mitochondria), and prevents a number of artifacts caused by routine GO fixation. Morphology can also be improved by using DMSO in conjunction with GO.

Phosphorylation and the actin cytoskeleton in defective newborn neutrophil chemotaxis

We have investigated the role of actin polymerization in the defective polymorphonuclear neutrophil (PMN) chemotaxis of the human newborn, and its regulation by protein kinase C and by phosphatases 1 and 2A. Isolated PMNs from adult volunteers and healthy term newborns, i.e. umbilical cord blood, were studied. Chemotaxis was measured by a modified micropore filter assay, and actin polymerization was assessed by flow cytometry. Chemotaxis of newborn PMNs (median 18 microm, range 9-21 microm) was significantly reduced compared with adult PMNs (median 23 microm, range 17-34 microm) (p < 0.001). Coincubation with the protein kinase C inhibitor bisindolylmaleimide GF109203X, did not significantly alter chemotaxis, whereas coincubation with the phosphatase inhibitors calyculin A or okadaic acid caused parallel dose-dependent inhibition of chemotaxis in adult and newborn PMNs. Peak actin polymerization was reduced in newborn compared with adult PMNs in response to stimulation with formyl-methionyl-leucyl-phenylalanine and zymosan-activated serum, but was normal in response to phorbol myristate acetate. Prior incubation for 5 min with bisindolylmaleimide GF109203X, calyculin A, or okadaic acid caused no significant alterations in the actin polymerization response to stimulation with formyl-methionyl-leucyl-phenylalanine. We conclude that: 1) newborn PMNs have reduced actin polymerization in response to stimulation with chemotactic agents which act via cell surface receptors, but not with phorbol myristate acetate, which acts directly in the cytoplasm. This suggests that a defect in cell signal transduction may be an underlying factor in defective newborn PMN chemotaxis. 2) Phosphatase inhibitors strongly inhibit chemotaxis but not actin polymerization, therefore phosphatases 1 and 2A may be important regulators of PMN chemotaxis, but this regulation takes place either at a point distal to actin polymerization or via another pathway. 3) Similar results in adult and newborn PMNs suggest that this is not the site of the underlying defect in newborn PMN chemotaxis.

HLA-DR alleles are associated with IDDM, but not with impaired neutrophil chemotaxis in IDDM

Insulin-dependent diabetes mellitus (IDDM) is a risk factor for periodontitis. Depressed neutrophil chemotaxis has been demonstrated in IDDM and in early-onset periodontitis (EOP). HLA-DR antigens are associated with both IDDM and periodontitis. This investigation sought to determine an association of HLA-DR3, -DR4, and -DR53 with impaired neutrophil chemotaxis in an IDDM sample. The neutrophil chemotaxis index of 41 diabetics and 27 controls was determined by a modified Boyden chamber method, and certain class II HLA genotypes were determined by polymerase chain-reaction amplification of genomic DNA by means of sequence-specific primers (PCR-SSP). The mean chemotaxis index of the diabetics was significantly less than that of the controls (p < or = 0.02). HLA-DR3 (p < or = 0.002), -DR4 (p < 0.003), and -DR53 (p < or = 0.001) were associated with IDDM. Neutrophil chemotaxis and glucose metabolism were not significantly correlated. None of the HLA-DR alleles was associated with impaired neutrophil chemotaxis. Therefore, the neutrophil chemotaxis defect of IDDM appears to be independent of these HLA-DR-associated genes.

Effect of major surgery on neutrophil chemotaxis and actin polymerization in neonates and children

The authors have examined the effect of major surgery in neonates and older children on neutrophil (PMN) chemotaxis and on actin polymerization, an essential early step in PMN movement. Isolated PMNs from the following subjects were studied: healthy adult volunteers (n = 28), healthy newborns (n = 21), newborns undergoing major surgery (n = 7), and older infants and children undergoing major surgery (n = 14). Chemotaxis was measured by a micropore filter assay, and actin polymerization was measured by flow cytometry. Blood samples from surgical patients were obtained preoperatively, hourly during the procedure, immediately postoperatively, and 48 hours after surgery. Mean preoperative newborn PMN chemotaxis was similar to that of healthy newborn PMN, and mean preoperative PMN chemotaxis in children was similar to that of healthy adults. There were no significant alterations in PMN chemotaxis during or after major surgery in neonates or children. Peak PMN actin polymerization, after stimulation with formyl methionyl leucyl phenylalanine (FMLP) (10 nm), was significantly diminished in healthy neonates compared with adults (P < .005). Preoperative surgical neonates had similar peak PMN actin polymerization levels to those of healthy newborns, and older preoperative children had similar levels to adults. PMN actin polymerization did not significantly change during or after major surgery. Despite reductions in PMN chemotaxis and actin polymerization in healthy neonates, there is no further impairment of these PMN functions during or after major surgery. Our data suggest that PMN chemotactic function is resistant to the stress of uncomplicated major surgery in neonates and children.

Interleukin-10 promotes anti-collagen antibody production in type I diabetic peripheral B lymphocytes

Previous studies have shown that type I diabetes (IDDM) increases the risk of developing periodontitis by 2-3-fold. IDDM patients exhibit destruction of the pancreatic beta cells, most probably caused by an autoimmune reaction. Evidence is accumulating to support the role of the autoimmune response in periodontal pathogenesis. A cytokine, interleukin (IL)-10, has been reported to selectively promote the expansion of a B lymphocyte lineage (CD5/LY1/B1) which has the propensity for secreting high levels of autoantibody. Therefore, the purpose of this project was to evaluate IL-10 production, percentage of CD5 B cells and the frequency of anti-collagen secreting cells in peripheral blood mononuclear cells of age, gender and race matched IDDM patients and controls. IL-10 production was evaluated by an ELISA using the supernatant of adherent peripheral blood cells cultured for 24 h in the presence of Porphyromonas gingivalis lipopolysaccharide (LPS). In 8 of 31 patients, IL-10 levels were significantly increased in IDDM compared to controls and a higher percentage of CD5 B cells was also observed by flow cytometry. In addition, these patients exhibited a higher frequency of anti-collagen secreting cells as elucidated by an ELISPOT. Moreover, treatment with a neutralizing anti-IL-10 antibody diminished the anti-collagen antibody response by 70%. These findings support the concept that a subset of IDDM patients possess an extremely robust IL-10 response following exposure to Gram-negative LPS, which could predispose them to the development of periodontitis through a heightened autoimmune mechanism.

Lipopolysaccharide isolated from Porphyromonas gingivalis grown in hemin-limited chemostat conditions has a reduced capacity for human neutrophil priming

One way prokaryotes respond to environmental stresses is by modifying selected outer membrane components. Iron, in the form of hemin, has been shown to be a significant regulator of Porphyromonas gingivalis growth and virulence and of the expression of outer membrane proteins and lipopoly saccharide. Since lipopoly saccharide has profound effects on host immune cells, this study compared the effect of hemin-restricted and hemin-normal P. gingivalis growth conditions on lipopolysaccharide priming of N-formylmethionyl-leucyl-phenylalanine-induced superoxide generation by human neutrophils. P. gingivalis was grown in a chemostat under normal (5 micrograms hemin/ml) and hemin-restricted (0.08 microgram hemin/ml) conditions. Purified lipopolysaccharide from both P. gingivalis normal and hemin-limited environments increased N-formylmethionyl-leucyl-phenylalanine-induced superoxide release by neutrophils in a dose-dependent manner. Lipopolysaccharide isolated from the hemin-normal conditions was a significantly more potent neutrophil priming agent than the lipopolysaccharide isolated from hemin-restricted conditions. Addition of normal human serum enhanced the priming effect of both lipopolysaccharide preparations; this effect, however, was more evident with the hemin-normal lipopolysaccharide. Further, this enhancing effect of serum was partly reduced in the presence of antibodies raised against the serum lipopolysaccharide-binding protein. The differences in the biological activity of the two lipopolysaccharide preparations could be associated with structural differences detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. These results indicate that hemin availability affects regulation of an aspect of P. gingivalis virulence, lipopolysaccharide-human neutrophils priming. The reduced capacity for neutrophil priming by hemin-restricted lipopolysaccharide appears to be related to lipopolysaccharide-neutrophil interactions and not to serum factors Targeting bacterial cell-surface components involved in hemin transport might be effective therapy for P. gingivalis-associated periodontal diseases.

Defective neutrophil actin polymerisation and chemotaxis in stressed newborns

Abnormalities of polymorphonuclear leukocyte (PMN) function contribute to high rates of postoperative infection in the newborn and to the vulnerability of newborns to overwhelming bacterial and fungal sepsis. The authors investigated (1) the effects of major surgery and sepsis on PMN chemotaxis in the newborn and (2) the role of cytoskeletal rearrangements in regulating chemotaxis. The subjects studied included newborns with sepsis (n = 16), newborns who underwent major surgery (n = 7), healthy full-term newborns (n = 21), and healthy adult volunteers (n = 28). Peak actin polymerisation was diminished in all newborns (relative to the adults) after stimulation with formyl methionyl leucyl phenylalanine (FMLP) (10 nmol/L), and with zymosan activated serum (ZAS) (10%). Major surgery and sepsis in newborns caused no further reduction in actin polymerisation. Changes in PMN shape after stimulation with FMLP were reduced in the newborns. PMN chemotaxis was significantly lower in healthy newborns than in adults (17 +/- 4 microns v 24 +/- 5 microns; P < .0001) and was even lower in septic newborns (11 +/- 4 microns; P < .005). Surgery and anaesthesia did not alter chemotaxis.

Lipopolysaccharide priming of superoxide release by human neutrophils: role of membrane CD14 and serum LPS binding protein

Previous studies have suggested that lipopolysaccharide (LPS) interactions with neutrophils and monocytes are mediated via the CD14 receptor, in the presence of serum factors such as LPS-binding protein (LBP) and septin. The present study was designed to test if CD14-mediated LPS priming of human neutrophils is dependent upon the presence of serum proteins and to evaluate the contribution of serum factors in LPS-neutrophil interactions. The results demonstrate that CD14 mediates the priming of neutrophil superoxide release by LPS both in the presence and in the absence of serum. However, priming by LPS is greatly enhanced in the presence of human serum, and the factor responsible for this phenomenon is LBP and not heat-sensitive proteins, such as septin.

Degradation of humoral host defense by Candida albicans proteinase

The effect of an extracellular proteinase from the pathogenic yeast Candida albicans on the bactericidal and opsonizing activities of human serum was studied. The ability of human polymorphonuclear leukocytes to kill Staphylococcus aureus was greatly reduced when the bacteria were opsonized with human serum treated with the proteinase. The reduction in the opsonizing activity of human serum was attributed to degradation of the Fc portion of immunoglobulin G by the action of C. albicans proteinase as determined by immunoprecipitation reaction. However, the Fab portion of immunoglobulin G was resistant to proteolysis by the proteinase. A clear reduction in the bactericidal activity of human serum against Escherichia coli was observed when the serum was treated with C. albicans proteinase. The reduction of serum bactericidal activity was attributed to the degradation of complement C3 by proteolysis by the proteinase as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while C5 resisted the action of the proteinase. As determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the proteinase also degrades endogenous proteinase inhibitors, such as alpha 2 macroglobulin and alpha 1 proteinase inhibitor, which are involved in regulating inflammation. These results suggest that destruction of a host's defense-oriented or regulatory proteins facilitates debilitation of the infected host.

Impaired bactericidal activity of PMN from two brothers with necrotizing ulcerative gingivo-periodontitis

The purpose of this study was to investigate the pathogenesis of necrotizing ulcerative gingivo-periodontitis (ANUP) diagnosed in two brothers, age 9 (ANUP1) and 14 (ANUP2) from rural Egypt. Complete blood count, differential and blood chemistry were within normal limits for both brothers and they were not malnourished. The phagocytosis and killing function of their polymorphonuclear leukocytes (PMN) towards four bacterial species were assessed using a fluorochrome microassay. The selection of bacterial species was based on preliminary microbiological results in early onset periodontitis in Egypt. Fluorochrome-labeled Prevotella intermedia, Peptostreptococcus micros, Campylobacter rectus, and Porphyromonas gingivalis were pre-opsonized with ANUP serum and added to PMN from both ANUP patients, as well as PMN from three sex-matched and two sex- and age-matched healthy Egyptian control (CTL) subjects. We found significant depressions (P < 0.05) in PMN phagocytosis and killing of C. rectus and P. intermedia by ANUP1 and ANUP2, when compared to all CTL PMN. An assessment of the Gram-negative subgingival microflora present in both ANUP patients (in colony forming unit percent of total CFU recovered) (CFU %) revealed the presence of P. intermedia (ANUP1, 41.7 CFU %; ANUP2, 14.8 CFU %), Fusobacterium nucleatum (ANUP1, 3.6 CFU %; ANUP2, 48.1 CFU %), and Veillonella spp. (ANUP1, 18.2 CFU %; ANUP2, 18.5 CFU %). Spirochetes were also observed in cytocentrifuged, Gram-stained plaque from both ANUP patients. The predominant Gram-positive bacterial species recovered from both NUG1 and NUG2 was Streptococcus morbillorum.

Calcium-dependent protein kinase C activity of neutrophils in localized juvenile periodontitis

Protein kinase C is a key molecule in neutrophil signal transduction after receptor stimulation by soluble bioactive molecules. It has been reported that neutrophils from most patients with localized juvenile periodontitis (LJP) do not have a normal response after stimulation with a chemotactic ligand such as N-formylmethionylleucylphenylalanine (FMLP). To further clarify the mechanism of this altered response and to confirm and expand earlier observations, the calcium-dependent protein kinase C activity of neutrophils from patients with LJP was evaluated. Peripheral blood neutrophils from 12 patients and 12 healthy subjects, age, sex, and race matched, were sonicated and subsequently subfractionated by ultracentrifugation into a soluble fraction (cytosol rich) and a particulate fraction (membrane rich). The calcium-dependent protein kinase C activity was evaluated in each fraction by phosphorylation of histone with radiolabeled ATP in the presence or in the absence of phorbol 12-myristate 13-acetate stimulation. Results revealed that the total calcium-dependent protein kinase C activity of neutrophils from patients with LJP and depressed chemotactic migration to FMLP (201.0 +/- 63.6 pmol/min/10(7) cells) was lower than that of neutrophils from healthy subjects (287.6 +/- 55.7 pmol/min/10(7) cells) (P < 0.01). The calcium-dependent protein kinase C activity in neutrophils from patients with LJP exhibited a positive correlation with chemotactic migration to FMLP (P < 0.05). The low activity of calcium-dependent protein kinase C in neutrophils from the patients reflected the low activity in the soluble fraction from the neutrophils. After stimulation with phorbol 12-myristate 13-acetate, the calcium-dependent protein kinase C activity was found to be lower from patients with LJP than from healthy subjects. These results suggest that lower calcium-dependent protein kinase C in neutrophils is a predisposing factor for LJP.

Further characterization of the neutrophil oxidative burst by flow cytometry

The ability to generate reactive oxygen species is essential for neutrophils to kill infectious micro-organisms. We have investigated the 'oxidative burst' in human neutrophils stimulated in vitro with either opsonized zymosan (OZ) or phorbol myristate acetate (PMA) at the single cell level by flow cytometry using dichlorofluorescein diacetate (DCFH-DA) and dihydrorhodamine 123 (DHR) as oxidative probes. These responses have been compared to results obtained with chemiluminescence and spectrophotometric assays. DHR was the most sensitive oxidative probe and PMA the more potent stimulus. The magnitude of the intracellular fluorescence generated with both probes was increased substantially by inhibiting the activities of H2O2-consuming enzymes with a relatively low concentration of azide, which also influenced the distribution of neutrophil subpopulations that expressed fluorescence differentially. Positive correlations between the DCFH-DA and DHR assays were found with both stimuli, and between these assays and ferricytochrome c reduction with OZ-stimulated cells only. We conclude that the DHR flow cytometric assay is the most sensitive technique available for investigating changes that may occur in the oxidative activities and distribution patterns of active neutrophil subpopulations in response to a variety of physiological and pathological conditions.

Measurement of ascorbic acid in platelets and its relationship to polymorphonuclear leukocyte levels

A simplified method for measuring ascorbic acid (AA) concentrations in platelets is described. Platelet ascorbate was determined as the difference in concentrations between platelet rich plasma and platelet free plasma. In 20 healthy individuals concentrations of AA in platelets and polymorphonuclear leukocytes were found to be significantly correlated (r = 0.72, P < 0.01). Measurement of platelet ascorbate may provide an estimate of tissue AA status.