Itamar Shalit

Genomic Approach to Identification of Mutations Affecting Caspofungin Susceptibility in Saccharomyces cerevisiae

ABSTRACT The antifungal agent caspofungin (CAS) specifically interferes with glucan synthesis and cell wall formation. To further study the cellular processes affected by CAS, we analyzed a Saccharomyces cerevisiae mutant collection (4,787 individual knockout mutations) to identify new genes affecting susceptibility to the drug. This collection was screened for increased CAS sensitivity (CAS-IS) or increased CAS resistance (CAS-IR). MICs were determined by the broth microdilution method. Disruption of 20 genes led to CAS-IS (four- to eightfold reductions in the MIC). Eleven of the 20 genes are involved in cell wall and membrane function, notably in the protein kinase C (PKC) integrity pathway (MID2, FKS1, SMI1, and BCK1), chitin and mannan biosynthesis (CHS3, CHS4, CHS7, and MNN10), and ergosterol biosynthesis (ERG5 and ERG6). Four of the 20 genes (TPO1, VPS65, VPS25, and CHC1) are involved in vacuole and transport functions, 3 of the 20 genes (CCR4, POP2, and NPL3) are involved in the control of transcription, and 2 of the 20 genes are of unknown function. Disruption of nine additional genes led to CAS-IR (a fourfold increase of MIC). Five of these nine genes (SLG1, ERG3, VRP1, CSG2, and CKA2) are involved in cell wall function and signal transduction, and two of the nine genes (VPS67 and SAC2) are involved in vacuole function. To assess the specificity of susceptibility to CAS, the MICs of amphotericin B, fluconazole, flucytosine, and calcofluor for the strains were tested. Seven of 20 CAS-IS strains (with disruption of FKS1, SMI1, BCK1, CHS4, ERG5, TPO1, and ILM1) and 1 of 9 CAS-IR strains (with disruption of SLG1) demonstrated selective susceptibility to CAS. To further explore the importance of PKC in CAS susceptibility, the activity of the PKC inhibitor staurosporine in combination with CAS was tested against eight Aspergillus clinical isolates by the microdilution assay. Synergistic or synergistic-to-additive activities were found against all eight isolates by use of both MIC and minimum effective concentration endpoints.

Anti-Inflammatory Effects of Moxifloxacin on Activated Human Monocytic Cells: Inhibition of NF-kappaB and Mitogen-Activated Protein Kinase Activation and of Synthesis of Proinflammatory Cytokines

ABSTRACT We previously showed that moxifloxacin (MXF) exerts protective anti-inflammatory effects in immunosuppressed mice infected with Candida albicans by inhibiting interleukin-8 (IL-8) and tumor necrosis factor alpha (TNF-α) production in the lung. Immunohistochemistry demonstrated inhibition of nuclear factor (NF)-κB translocation in lung epithelium and macrophages in MXF-treated mice. In the present study we investigated the effects of MXF on the production of proinflammatory cytokines (i.e., IL-8, TNF-α, and IL-1β) by activated human peripheral blood monocytes and THP-1 cells and analyzed the effects of the drug on the major signal transduction pathways associated with inflammation: NF-κB and the mitogen-activated protein kinases ERK and c-Jun N-terminal kinase (JNK). The levels of IL-8, TNF-α, and IL-1β secretion rose 20- and 6.7-fold in lipopolysaccharide (LPS)-activated monocytes and THP-1 cells, respectively. MXF (5 to 20 μg/ml) significantly inhibited cytokine production by 14 to 80% and 15 to 73% in monocytes and THP-1 cells, respectively. In THP-1 cells, the level of NF-κB nuclear translocation increased fourfold following stimulation with LPS-phorbol myristate acetate (PMA), and this was inhibited (38%) by 10 μg of MXF per ml. We then assayed the degradation of inhibitor (I)-κB by Western blotting. LPS-PMA induced degradation of I-κB by 73%, while addition of MXF (5 μg/ml) inhibited I-κB degradation by 49%. Activation of ERK1/2 and the 46-kDa p-JNK protein was enhanced by LPS and LPS-PMA and was significantly inhibited by MXF (54 and 42%, respectively, with MXF at 10 μg/ml). We conclude that MXF suppresses the secretion of proinflammatory cytokines in human monocytes and THP-1 cells and that it exerts its anti-inflammatory effects in THP-1 cells by inhibiting NF-κB, ERK, and JNK activation. Its anti-inflammatory properties should be further assessed in clinical settings.

In vitro synergy of caspofungin and itraconazole against Aspergillus spp.: MIC versus minimal effective concentration end points

ABSTRACT Caspofungin and itraconazole were studied alone and in combination against 31 clinical isolates of Aspergillus spp. according to NCCLS M38-P guidelines. MICs and microscopic minimal effective concentrations (MECs) were recorded, and synergy was calculated by using both end points. Synergy or synergy to additivity was found in 30 of 31 isolates by using MIC end points. With MEC end points no synergy was found and indifference was detected in 26 of 31 strains.

Immunomodulatory and Protective Effects of Moxifloxacin against Candida albicans-Induced Bronchopneumonia in Mice Injected with Cyclophosphamide

ABSTRACT In a previous study, moxifloxacin was shown to ameliorate immunosuppression and enhance cytokine production in several tissues, including the lungs of cyclophosphamide-injected mice. We examined here the effects of moxifloxacin on Candida albicans lung infection in cyclophosphamide-injected mice. Mice were injected on day 0 with 250 mg of cyclophosphamide/kg, and on days 1 to 4 they were given moxifloxacin at 22.5 mg/kg/day compared to controls given ceftazidime at 75 mg/kg/day or saline. On day 6, C. albicans (10 7 CFU/mouse) was inoculated intratracheally, and animals were observed for the development of bronchopneumonia, weight loss, mortality, the presence of C. albicans, and lung cytokine production. Histopathology on day 10 postinoculation revealed bronchopneumonia in 50, 67, and 0% of saline-, ceftazidime-, and moxifloxacin-treated mice, respectively (P < 0.05). The mortality rates were 28, 17, and 5%, respectively (P < 0.05), and weight loss occurred at 20, 32, and 0%, respectively (P < 0.05). By day 15, C. albicans was eliminated from all moxifloxacin-treated mice but was still isolated from lung homogenates of 50 to 60% of the saline- and ceftazidime-treated groups. Among the cytokines tested on days 0 to 15, we found an increased production of tumor necrosis factor alpha, KC (functional interleukin-8), and gamma interferon in the lungs of ceftazidime- and saline-treated controls compared to the moxifloxacin pretreatment that abolished their secretion. In conclusion, moxifloxacin protected cyclophosphamide-injected mice from C. albicans-induced lung infection and significantly reduced pneumonia, weight loss, and mortality despite the lack of direct antifungal activity. This is most likely due to an immunomodulating activity conferred by moxifloxacin, as shown in this model and in our previous studies. Its potential protective role should be studied in patients undergoing chemotherapy and immune suppression.

Immunomodulatory effects of moxifloxacin in comparison to ciprofloxacin and G‐CSF in a murine model of cyclophosphamide‐induced leukopenia

Abstract: We analyzed the effect of the two quinolones moxifloxacin and ciprofloxacin on the repopulation of hematopoietic organs and on the production of cytokines by various organs of cyclophosphamide (CP)‐induced leukopenic mice. The effect was compared to that of G‐CSF. Cyclophosphamide injection induced a severe leukopenia, with nadir at day 4 post‐injection. All the quinolone and G‐CSF‐treated animals showed WBC>500/μL at the nadir, compared to 50% of saline‐treated mice. Cyclophosphamide induced a marked decrease in the number of myeloid progenitors (CFU‐C) in bone marrow (BM) and spleen. Quinolone or G‐CSF treatment resulted in a 1.4–4.3‐fold increase in CFU‐C numbers in the BM; no enhancement was observed in the spleen. Treatment with CP resulted in enhanced colony‐stimulating activity (CSA) in bone shaft and spleen and decreased activity in bladder and lung. Treatment of CP‐injected mice with quinolones significantly enhanced CSA in the bone shaft, spleen, lung and bladder on different days.

Infectious complications of peripherally inserted central venous catheters in children.

Background: Peripherally inserted central venous catheters (PICCs) are frequently used in infants and children. However, only limited data are available on current infectious and noninfectious complications of PICCs in this patient population. The aim of the study is to define the current rate of infectious and noninfectious complications of PICCs, the causative agents, and to define possible risk factors associated with these complications. Methods: A prospective surveillance study was conducted at the Schneider Children Medical Center of Israel. All patients in whom a PICC was inserted between August 2004 and October 2006 were included. Demographic, clinical, and microbiologic data were collected by a questionnaire completed by the anesthesiologist at the time of insertion and removal of each catheter. Items covered epidemiologic, clinical, and microbiologic data. Results: A total of 279 PICCs were inserted in 221 patients. There were no complications at insertion. Mean dwell time was 30 days. One hundred seventy-seven (63%) of all PICC placements were free of complications. Twenty-six catheters (9.3%) were dislodged accidentally; 38 (13.6%) were removed for mechanical problems: tears in 5, leaks in 12, and obstructions in 21; 38 (13.6%) were removed for an infectious complication: phlebitis in 13 (4.6%, 1.5/1000 PICC days), exit-site infection in 10 (3.5%, 1.1/1000 PICC days), PICC-associated bloodstream infection in 12 (4.3%, 1.4/1000 PICC days), and PICC-related bloodstream infection in 4 (1.4%, 0.4/1000 PICC days); 15 more were removed for presumed infection (5.3%, 1.7/1000 PICC days). On multivariate analysis, composite indication for PICC use and older patient age were significantly associated with infectious complications. Conclusions: PICCs are safe and may be used for prolonged periods. In our center, the rates of infectious complications are lower than for tunneled central venous catheters. Accidental dislodgement is not uncommon and may be prevented by use of sutures, occlusive dressing, and education of patients, families, and medical staff.

Transplanted Hematopoietic Cells Seed in Clusters in Recipient Bone Marrow In Vivo

The process of hematopoietic stem and progenitor cell (HSPC) seeding in recipient bone marrow (BM) early after transplantation is not fully characterized. In vivo tracking of HSPCs, labeled with PKH dyes, through an optical window surgically implanted on the mouse femur revealed that transplanted cells cluster in the recipient BM. Within the first day after intravenous injection, 86 ± 6% of the cells seeded in clusters (p < 0.001 versus scattered cells) in the endosteal surfaces of the epiphyses. The primary clusters were formed by concomitant seeding of 6‐10 cells over an area of ∼70 μm, and secondarily injected cells did not join the already existing clusters but formed new clusters. Major antigen‐disparate HSPCs participated in formation of the primary clusters, and T lymphocytes were also incorporated. After 4 to 5 days, some cellular clusters were observed in the more central regions of the BM, where the brightness of PKH fluorescence decreased, indicating cellular division. These later clusters were classified as secondary, assuming that the mechanisms of migration in the BM might be different from those of primary seeding. Some clusters remained in the periphery of the BM and retained bright fluorescence, indicating cellular quiescence. The number of brightly fluorescent cells in the clusters decreased exponentially to two to three cells after 24 days (p < 0.001). The data suggest that the hematopoietic niche is a functional unit of the BM stromal microenvironment that hosts seeding of a number of transplanted cells, which form a cluster. This may be the site where auxiliary non‐HSPC cells, such as T lymphocytes, act in support of HSPC engraftment.

Candida endocarditis in neonates: report of five cases and review of the literature

Candidal endocarditis is an uncommon and serious complication of invasive Candida infection in neonates. The aim of this study was to further characterise candidal endocarditis in neonates. Between 1995 and 2000, 56 patients were diagnosed with Candida bloodstream infections (CBSI) in the Neonatal Intensive Care Unit of Schneider Childrens Medical Center of Israel. Five of them (9%) developed mycetoma of the right atrium. None of the patients had congenital heart disease or a central venous catheter in the right heart at the time of diagnosis. All were treated with amphotericin B alone or in combination with other antifungals, without surgical intervention. One patient died of the disease and one died later of polymicrobial sepsis and necrotizing enterocolitis. A review of the literature since 1980 yielded an additional 25 cases of candidal endocarditis. For the whole sample (n = 30) survival rate was 73.1%. Six of the 10 patients treated with antifungal agents and surgery survived (60%), compared with 13 of the 20 patients treated only medically (65%) (P = 1.0). Candida endocarditis in neonates differs from fungal endocarditis in adults in risk factors, clinical presentation and outcome. As the outcome of surgical and medical treatment are comparable, antifungal therapy alone may be a valid therapeutic option in high‐risk cases.

Immunomodulatory effects of ciprofloxacin in TNBS-induced colitis in mice

Background Crohns exacerbation and pouchitis are commonly treated with ciprofloxacin and metronidazole. Few studies have shown an advantage of this regimen compared with other antibiotics. Most attributed the effect to its better antibacterial coverage. Others have shown an apparent anti‐inflammatory effect of quinolones in several in vitro and in vivo models of inflammation other than inflammatory bowel diseases (IBD). Our objective was to test the hypothesis that ciprofloxacin may act as an anti‐inflammatory agent rather than just an antibacterial drug using a model of chemical colitis. Methods TNBS colitis was induced in BALB/c mice. The anti‐inflammatory effect of ciprofloxacin compared with ceftazidime and dexamethasone was assessed. Results Mice treated with ciprofloxacin (7.5 mg/kg or 15 mg/kg) had significant reductions in clinical signs, body weight loss, splenic and colonic weight increase compared with saline‐treated and ceftazidime‐treated mice. Histologic analysis showed mild inflammation in ciprofloxacin‐treated mice with a mean score of 3.8 ± 0.5 points compared with moderate colitis scored 7.8 ± 1.3 and 9.5 ± 0.5 points in saline and ceftazidime‐treated mice, respectively. Analysis of cytokine levels in colon homogenates showed a significant decrease of IL‐1&bgr;, IL‐8, and TNF&agr; levels in ciprofloxacin‐treated animals. Immunohistochemistry for NF&kgr;B showed strong positivity in saline and ceftazidime‐treated mice in contrast to weak focal stain in ciprofloxacin‐ and dexamethasone‐treated mice. Conclusions These findings imply that ciprofloxacin has an anti‐inflammatory effect, rather than just an antibacterial one, making its use favorable in IBD patients. (Inflamm Bowel Dis 2007)

Interferon-gamma and bacterial lipopolysaccharide act synergistically on human neutrophils enhancing interleukin-8, interleukin-1beta, tumor necrosis factor-alpha, and interleukin-12 p70 secretion and phagocytosis via upregulation of toll-like receptor 4.

In human neutrophils, interferon (IFN)-&ggr; enhanced the expression of toll-like receptor 4 (TLR4), a crucial component of the signaling receptor complex for bacterial lipopolysaccharide (LPS). Lipopolysaccharide alone did not affect TLR4 expression, but costimulation with IFN-&ggr; and LPS induced higher levels of TLR4 expression than stimulation with IFN-&ggr; alone. Using the protein synthesis inhibitor cycloheximide and measuring the expression of CD35 in neutrophils stimulated with IFN-&ggr; and LPS alone or in combination, we could demonstrate that IFN-&ggr; enhances TLR4 by de novo protein synthesis, whereas the addition of LPS acts synergistically by enhancing vesicular mobilization to the cell surface. Costimulation with IFN-&ggr; and LPS induced neutrophil activation and enhanced secretion of the cytokines, interleukin (IL)-8, IL-1&bgr;, tumor necrosis factor-&agr;, and IL-12 p70, and phagocytosis of latex beads, processes that were blocked by a monoclonal antibody specific for TLR4. These data suggest that IFN-&ggr; primes neutrophils to respond to LPS.