In vitroandin vivoeffects of Imipenem on phagocytic activity of murine peritoneal macrophages

Extracellular CIRP dysregulates macrophage bacterial phagocytosis in sepsis

In sepsis, macrophage bacterial phagocytosis is impaired, but the mechanism is not well elucidated. Extracellular cold-inducible RNA-binding protein (eCIRP) is a damage-associated molecular pattern that causes inflammation. However, whether eCIRP regulates macrophage bacterial phagocytosis is unknown. Here, we reported that the bacterial loads in the blood and peritoneal fluid were decreased in CIRP^-/- mice and anti-eCIRP Ab-treated mice after sepsis. Increased eCIRP levels were correlated with decreased bacterial clearance in septic mice. CIRP^-/- mice showed a marked increase in survival after sepsis. Recombinant murine CIRP (rmCIRP) significantly decreased the phagocytosis of bacteria by macrophages in vivo and in vitro. rmCIRP decreased the protein expression of actin-binding proteins, ARP2, and p-cofilin in macrophages. rmCIRP significantly downregulated the protein expression of βPIX, a Rac1 activator. We further demonstrated that STAT3 and βPIX formed a complex following rmCIRP treatment, preventing βPIX from activating Rac1. We also found that eCIRP-induced STAT3 phosphorylation was required for eCIRP's action in actin remodeling. Inhibition of STAT3 phosphorylation prevented the formation of the STAT3-βPIX complex, restoring ARP2 and p-cofilin expression and membrane protrusion in rmCIRP-treated macrophages. The STAT3 inhibitor stattic rescued the macrophage phagocytic dysfunction induced by rmCIRP. Thus, we identified a novel mechanism of macrophage phagocytic dysfunction caused by eCIRP, which provides a new therapeutic target to ameliorate sepsis.

Meropenem: effects on human leukocyte functions and interleukin release

Modifications of the immune response have been reported for a number of antimicrobial agents following both in vivo and in vitro experiments. Present results were obtained from in vitro incubated human polymorphonuclear cells (PMN) and monocytes treated with meropenem, a novel carbapenem antibiotic. Only the highest concentrations of meropenem (50-200 microg/ml) significantly reduced the phagocytic activity and unstimulated superoxide release of neutrophils after 1 h of incubation. Moreover meropenem (100 and 200 microg/ml) reduced PMA-stimulated superoxide release by PMN after 1 h of incubation. Only the highest concentration used (200 microg/ml) was found to reduce significantly superoxide release by PMA-unstimulated and -stimulated PMN incubated for 2 h. Meropenem did not affect some of the PMN functions studied (killing of Candida albicans, chemotaxis and glucose consumption) over a broad range of concentrations (5, 10, 20, 50, 100, 200 microg/ml). The leukocyte viability did not change even at the highest antibiotic concentration used, as showed by the trypan blue exclusion test. The LPS-induced release of IL-1alpha, IL-6 and IL-8 from isolated monocytes was not impaired by meropenem (100 and 200 microg/ml), that significantly reduced TNFalpha stimulated by LPS, after 4 h of incubation. In conclusion our data suggest that therapeutically relevant concentrations (5-20 microg/ml) of meropenem did not modify substantially the viability and the functions of human leukocytes.

Synthesis, structural characterization and influence on the phagocytic activity of human neutrophils of thiazoline and thiazine derivative ligands and their zinc(II) complexes

The zinc(II) complexes dichloro[2-(3,4-dichlorophenyl)imino-kappaN-(2-thiazolin-kappaN-2-yl)thiazolidine]zinc(II) (1) and dichloro[2-(3,4-dichlorophenyl)imino-kappaN-(4H-5,6-dihydro-1,3-thiazin-kappaN-2-yl)tetrahydrothiazine]zinc(II) (2) have been isolated and characterized in the solid state by X-ray diffraction, elemental analysis and IR spectra. In both complexes, the environment around the zinc(II) ion may be described as a distorted tetrahedral geometry, with the metallic atom coordinated to two chlorine atoms [Zn-Cl(1)=2.218(1)A; Zn-Cl(2)=2.221(1)A], one imino nitrogen [Zn-N(3)=2.042(2)A] and one thiazoline nitrogen [Zn-N(1)=2.022(2)A] in complex 1 and to two chlorine atoms [Zn-Cl(1)=2.216(1)A; Zn-Cl(2)=2.192(1)A], one imino nitrogen [Zn-N(3)=2.045(2)A] and one thiazine nitrogen [Zn-N(1)=2.039(2)A] in complex 2. In addition, we also report in this study the crystal structure of the 2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine (TdTn) ligand as well as the synthesis and characterization by X-ray diffraction, (1)H and (13)C NMR spectra, elemental analysis, IR and electronic spectra of the 2-(3,4-dichlorophenyl)imino-N-(4H-5,6-dihydro-1,3-thiazin-2-yl)tetrahydrothiazine (TzTz) ligand. Besides, we study the phagocytic function in humans neutrophils treated with each complex and ligand aforementioned.

Evaluation of biocompatibility of sodium perborate and 30% hydrogen peroxide using the analysis of the adherence capacity and morphology of macrophages

OBJECTIVE

The purpose of this study was to evaluate the biocompatibility of the most used bleaching materials for pulpless teeth, sodium perborate and 30% hydrogen peroxide, in an experimental model of macrophages, through analysis of the adherence index and the cellular morphology.

METHODS

Inflammatory macrophages were obtained from peritoneal washed of Wistar rats. The evaluation of the adherence capacity of these cells to the plastic surface was conducted in Eppendorf tubes containing RPMI, after treatment with the bleaching agents diluted in 1:10, 1:100 and 1:1000 for 15 and 30 min, and incubation at 37 degrees C and humidified atmosphere of 5% CO(2) in air. The cellular morphology was verified after incubation of the cells treated with the bleaching agents in culture plaques and compared with normal cells in culture medium.

RESULTS

Results showed that sodium perborate neither increased the adherence index, nor altered the cellular morphology when compared to the control group. The distribution, cellular morphology, cytoplasmatic and nuclear characteristics, reproduced the aspects observed in normal macrophages. However, the treatment with 30% hydrogen peroxide presented an increase in adherence index when compared to the control group (RPMI), in all dilutions, according to Mann-Whitney test (n=08 and p=0.001 for dilutions 1:10 and 1:100, and n=08 and p=0.004 for dilution 1:1000). The morphology of the cells treated with this product presented structural alterations proportionally greater, depending on the dilution of this bleaching agent, and even in the highest dilution (1:1000) the cells presented very evident alterations.

CONCLUSIONS

This irreversible cellular damage as well as the elevation of the adherence index, characterizes the aggressive potential of 30% hydrogen peroxide, regardless of its dilution. Sodium perborate, on the other hand, showed biocompatibitity, since, no morphological nor functional alteration was observed in macrophages.

Septic mice are susceptible to pulmonary aspergillosis

Clinical data underscores the fact that subsequent high mortality rates occur in patients who survive acute septic episodes. Herein, we described a clinically relevant model of experimental sepsis that we believe will allow further investigation of the manner in which the pulmonary innate immune response is modulated after sepsis. C57BL/6 mice were subjected to cecal ligation and puncture (CLP) model, whereby the cecum was partially ligated and punctured nine times with a 21-gauge needle. This procedure was associated with 100% mortality at 3 days after surgery. In contrast, when mice subjected to CLP were treated with antibiotic beginning at 8 hours after surgery, and every 12 hours thereafter until 3 days, approximately 60% of the mice survived. Interestingly, CLP survivors quickly succumbed (100% mortality) to pulmonary infection when intratracheally challenged, at day 3 after CLP, with viable Aspergillus fumigatus conidia. No mortality was observed in conidia-challenged sham-operated mice. The defective innate immune response against A. fumigatus in CLP mice could not be explained by a failure of neutrophils to infiltrate the lungs. Instead, gene array analysis revealed that several components of the innate immune response, including the nuclear factor-kappaB signaling pathway, were down-regulated. Thus, we describe a system of sepsis-induced innate immune failure in the lungs of C57BL/6 mice.

In vitro effect of cefodizime, imipenem/cilastatin and co-trimoxazole on dexamethasone and cyclosporin A depressed phagocytosis

Phagocytosis is an important part of the host defense against infection. Antibiotics can influence phagocytic function. In the present study, leukocyte metabolic response to phagocytic challenge by latex was assessed in relation to in vitro addition of cotrimoxazole, imipenem/cilastatin, cefodizime, dexamethasone (DXM), and/or cyclosporin A (CsA). Using latex particles as phagocytic challenge, glucose-1-14C utilization and 14CO2 production were measured by liquid scintillation counting. The phagocytic response was impaired by in vitro addition of DXM or CsA and this setup was used as an experimental model of immunodepression. The addition of co-trimoxazole to control samples (without DXM or CsA) depressed the response to latex challenge, whereas imipenem and cefodizime had a neutral effect. In the presence of DXM, co-trimoxazole induced a further decrease. The depressive effect of DXM was partially neutralized in the presence of cefodizime. With CsA depression, co-trimoxazole also induced a further decrease, imipenem had a neutral effect, while cefodizime partially restored the CsA suppressed reaction. Co-trimoxazole depressed the phagocytic response, imipenem had a neutral effect, whereas cefodizime restored the experimentally induced immunosuppression.

Immunomodulating effects of antibiotics: literature review

Antibiotics can interact directly with the immune system. This is a review of the immunomodulating effects of antibiotics. The Medline database on CD-ROM was searched for the years 1987 to 1994 using the following search string: "thesaurus explode antibiotics/all AND (thesaurus explode immune-system/drug effects OR thesaurus immune-tolerance/drug effects)." Aspects of the immune system studied were aspects of phagocyte functions: phagocytosis and killing, and chemotaxis and aspects of lymphocyte functions: lymphocyte proliferation, cytokine production, antibody production, delayed hypersensitivity and natural killer-cell activity. In order to quantify and to compare immunomodulatory properties of antibiotics we calculated an "immune index," defined as: number of positive statements--number of negative statements/total number of statements. Concerning phagocytosis, positive effects were observed for cefodizime, imipenem, cefoxitin, amphotericin B and clindamycin and negative effects for erythromycin, roxithromycin, cefotaxime, tetracycline, ampicillin and gentamicin. Clindamycin, cefoxition and imipenem induce enhancement of chemotaxis, whereas cefotazime, rifampicin and teicoplanin decrease chemotaxis. Regarding lymphocyte proliferation, cefodizime has the strongest stimulating effect, whereas tetracycline has the strongest negative effect. Except for erythromycin and amphotericin B the number of statements reported is too small to be conclusive for the interpretation of effects on cytokine production. Erythromycin and amphotericin B appear to stimulate cytokine production. As to antibody production, cefodizime has the strongest positive effect, whereas josamycin, rifampicin and tetracycline have marked negative effects. For delayed hypersensitivity and the natural killer-cell activity the number of statements is too small for any single antibiotic to be conclusive. There are three markedly immuno-enhancing antibiotics (imipenem, cefodizime and clindamycin) and eight markedly immuno-depressing antibiotics (erythromycin, roxithromycin, cefotaxime, tetracycline, rifampicin, gentamicin, teicoplanin and ampicillin).

Stimulation of phagocytic function in mouse macrophages by neurotensin and neuromedin N

The neuropeptides neurotensin and neuromedin N (from 10(-12) M to 10(-9) M) have been shown in this study to stimulate significantly in vitro several steps of the phagocytic process: adherence to substrate, chemotaxis, ingestion of inert particles (latex beads) and production of superoxide anion measured by nitroblue tetrazolium reduction in resting peritoneal macrophages from BALB/c mice. A dose-response relationship was observed, with a maximal stimulation of the phagocytic process at 10(-11) M. The two neuropeptides induced no change of intracellular cyclic AMP in murine macrophages. Moreover, adherence and chemotaxis decreased significantly in the presence of EGTA (1 mM), a chelator of extracellular Ca2+, or ryanodine (0.5 mM), a blocker of a Ca(2+)-gated channel from the endoplasmic reticulum, in both controls and samples with the addition of neurotensin or neuromedin N. These results suggest that there is no relation between the cAMP messenger system and the phagocytic process stimulation in murine peritoneal macrophages by neurotensin or neuromedin N. In addition, the results observed with EGTA and ryanodine could indicate that these two neuropeptides produce their effects through an increase of intracellular Ca2+ concentration.

Stimulation of the phagocytic function in guinea pig peritoneal macrophages by physical activity stress

A study was made of all the different stages of the phagocytic function in peritoneal macrophages from male guinea pigs [3 (SD 1) months old] before, immediately after, and 24 h after being subjected to stress from physical activity (swimming until exhaustion). The early (10 min) and late (40 min) adherence to tissue substrates, chemotaxis, attachment and phagocytosis of Candida albicans, ingestion of inert particles (latex beads), and basal oxidative metabolism [measured by nitroblue tetrazolium (NBT) reduction] were significantly stimulated by the physical activity. After 24 h, late adherence, attachment capacities, and basal oxidative metabolism returned to basal values, whereas early adherence, chemotaxis, phagocytosis of cells and inert particles, and microbicidal capacity (production of superoxide anion measured by NBT reduction in presence of ingested material) remained significantly increased. The stress produced by physical activity, reflected in increased serum corticosterone values, led to a global stimulation of the phagocytic function.