The effect of three broad-spectrum antimicrobials on mononuclear cell responses to encapsulated bacteria: evidence for down-regulation of cytokine mRNA transcription by trovafloxacin

Effect of Antimicrobial Agents on Inflammatory Cytokines in Acute Leptospirosis

The aim of this study was to assess the inflammatory cytokine response and possible association with antimicrobial treatment with penicillin, ceftriaxone, and doxycycline in acute leptospirosis. In the early acute stage, interleukin-10 (IL-10) levels were higher in mild cases than in severe cases (P = 0.01). IL-6 and IL-8 levels were low in patients who received >5 antimicrobial doses (P < 0.01). IL-8 levels were negatively correlated with the number of ceftriaxone doses administered (r = -0.315; P = 0.031). Further studies are needed to evaluate the possible downregulation of proinflammatory cytokines by ceftriaxone in leptospirosis.

Doxycycline suppresses Chlamydia pneumoniae induced interferon-gamma responses in peripheral blood mononuclear cells in children with allergic asthma

Persistent respiratory infections caused by Chlamydia pneumoniae have been implicated in the pathogenesis of chronic diseases (e.g. asthma). Antibiotics are used to treat C. pneumoniae respiratory infections; however, the use of antibiotics as anti-inflammatory agents in treatment of asthma remains controversial. The current study investigated whether ciprofloxacin, azithromycin, or doxycycline can suppress C. pneumoniae-induced production of immunoglobulin (Ig) E or cytokines in peripheral blood mononuclear cells (PBMC) obtained from asthmatic children. Apart from blood, nasopharyngeal swab specimens were also collected to test for the presence of C. pneumoniae and/or M. pneumoniae (qPCR). PBMC (1.5 x 10⁶) from asthmatic pediatric patients (N = 18) were infected or mock infected for 1 h ± C. pneumoniae AR-39 at a multiplicity of infection (MOI) = 0.1, and cultured ± ciprofloxacin, azithromycin, or doxycycline (0.1 or 1.0 μg/mLmL) for either 48 h (cytokines) or 10 days (IgE). Interleukin (IL)-4, interferon (IFN)-γ and IgE levels in supernatants were measured (ELISA). When PBMC were infected with C. pneumoniae, IL-4 and IFNγ production increased (p = 0.06 and 0.03, respectively); IgE levels were low. The now-elevated levels of IL-4 didn't decrease significantly after addition of ciprofloxacin, azithromycin, or doxycycline. However, infected PBMC IFNγ formation decreased significantly when 0.1 μg/mL doxycycline was employed (p = 0.04); no dose of ciprofloxacin or azithromycin had any impact. This inhibitory outcome with doxycycline lends support to the use of tetracyclines as immune modulators and anti-inflammatory medications in treatment of C. pneumoniae-infected asthma patients.

Surviving sepsis in the era of antibiotic resistance: are there any alternative approaches to antibiotic therapy?

Sepsis, a serious cause of morbidity in humans, has no proper single medication dedicated to it. In this review, we look at the current treatment modalities, the different approaches attempted towards treating it and alternative approaches that could be implemented to counter this neglected disease condition. The use of antibiotics towards treatment of sepsis, use of combinations and strategies derived from natural antimicrobial peptides have been dealt in detail. The social and technical difficulties associated with treating sepsis and the possible ways of combating them have also been discussed.

Trovafloxacin enhances lipopolysaccharide-stimulated production of tumor necrosis factor-α by macrophages: role of the DNA damage response

Trovafloxacin (TVX) is a drug that has caused idiosyncratic, drug-induced liver injury (IDILI) in humans. In a murine model of IDILI, otherwise nontoxic doses of TVX and the inflammagen lipopolysaccharide (LPS) interacted to produce pronounced hepatocellular injury. The liver injury depended on a TVX-induced, small but significant prolongation of tumor necrosis factor-α (TNF) appearance in the plasma. The enhancement of TNF expression by TVX was reproduced in vitro in RAW 264.7 murine macrophages (RAW cells) stimulated with LPS. The current study was designed to identify the molecular target of TVX responsible for this response in RAW cells. An in silico analysis suggested a favorable binding profile of TVX to eukaryotic topoisomerase II-α (TopIIα), and a cell-free assay revealed that TVX inhibited eukaryotic TopIIα activity. Topoisomerase inhibition is known to lead to DNA damage, and TVX increased the DNA damage marker phosphorylated histone 2A.X in RAW cells. Moreover, TVX induced activation of the DNA damage sensor kinases, ataxia telangiectasia mutated (ATM) and Rad3-related (ATR). The ATR inhibitor NU6027 [6-(cyclohexylmethoxy)-5-nitrosopyrimidine-2,4-diamine] prevented the TVX-mediated increases in LPS-induced TNF mRNA and protein release, whereas a selective ATM inhibitor [2-(4-morpholinyl)-6-(1-thianthrenyl)-4H-pyran-4-one (KU55933)] was without effect. TVX prolonged TNF mRNA stability, and this effect was largely attenuated by NU6027. These results suggest that TVX can inhibit eukaryotic topoisomerase, leading to activation of ATR and potentiation of TNF release by macrophages, at least in part through increased mRNA stability. This off-target effect might contribute to the ability of TVX to precipitate IDILI in humans.

Valnemulin downregulates nitric oxide, prostaglandin E2, and cytokine production via inhibition of NF-kappaB and MAPK activity

Valnemulin is a pleuromutilin antibiotic used in clinics for the treatment of various infections. We studied the in vitro anti-inflammatory effects of valnemulin and associated signal transduction mechanisms in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. We found that valnemulin inhibited nitric oxide (NO), prostaglandin E2 (PGE2), tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), and increased interleukin-10 (IL-10) production. Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression were also inhibited by valnemulin. We further observed that valnemulin prevented the LPS-induced NF-kappaB translocation from the cytoplasm into the nucleus. Valnemulin also blocked phosphorylation of three mitogen-activated protein kinases (MAPKs): extracellular signal receptor-activated kinase (ERK) 1/2, p38, and c-Jun N-terminal kinase (JNK). Our data indicate that valnemulin may have therapeutic anti-inflammatory effects independent of its antibacterial activity.

Differential effects of antibiotics in combination with G-CSF on survival and polymorphonuclear granulocyte cell functions in septic rats

BACKGROUND

In addition to their antimicrobial activity, antibiotics modulate cellular host defence. Granulocyte-colony stimulating factor (G-CSF) is also a well known immunomodulator; however little is known about the interactions of G-CSF with antibiotics. We investigated in septic rats the effects of two antibiotic combinations with G-CSF.

METHODS

In two clinic modelling randomised trials (CMRTs), male Wistar rats were anesthetized, given antibiotic prophylaxis, had a laparotomy with peritoneal contamination and infection (PCI), and were randomly assigned (n = 18 rats/group) to: 1) PCI only; 2) PCI+antibiotic; and, 3) PCI+antibiotic+G-CSF prophylaxis (20 mug/kg, three times). This sequence was conducted first with 10 mg/kg coamoxiclav, and then with ceftriaxone/metronidazole (Cef/met, 10/3 mg/kg). In additional animals, the blood cell count, migration and superoxide production of PMNs, systemic TNF-alpha and liver cytokine mRNA expression levels were determined.

RESULTS

Only the combination coamoxiclav plus G-CSF improved the survival rate (82 vs. 44%, p < 0.001). Improved survival with this combination was accompanied by normalised antimicrobial PMN migratory activity and superoxide production, along with normalised systemic TNF-alpha levels and a reduced expression of TNF-alpha and IL-1 in the liver.

CONCLUSION

There are substantial differences in the interaction of antibiotics with G-CSF. Therefore, the selection of the antibiotic for combination with G-CSF in sepsis treatment should be guided not only by the bacteria to be eliminated, but also by the effects on antimicrobial functions of PMNs and the cytokine response.

Lipopolysaccharide and trovafloxacin coexposure in mice causes idiosyncrasy-like liver injury dependent on tumor necrosis factor-alpha

Idiosyncratic adverse drug reactions (IADRs) occur in a small subset of patients, are unrelated to the pharmacological action of the drug, and occur without an obvious relationship to dose or duration of drug exposure. The liver is often the target of these reactions. Why they occur is unknown. One possibility is that episodic inflammatory stress interacts with the drug to precipitate a toxic response. We set out to determine if lipopolysaccharide (LPS) renders mice sensitive to trovafloxacin (TVX), a fluoroquinolone antibiotic linked to idiosyncratic hepatotoxicity in humans and if the cytokine tumor necrosis factor-alpha (TNFalpha) is involved in the development of liver injury. Male mice were treated with a nontoxic dose of TVX followed 3 h later by a nonhepatotoxic dose of LPS. Coexposure to TVX and LPS led to a significant increase in liver injury as determined by plasma alanine aminotransferase activity and histopathological examination. In contrast, coexposure of mice to LPS and levofloxacin (LVX), a fluoroquinolone without liability for causing IADRs in humans, was not hepatotoxic. Measurements of TNFalpha concentration in the plasma revealed a significant, selective increase in TVX/LPS-treated mice at times prior to and at the onset of liver injury. Treatment with either pentoxifylline to inhibit TNFalpha transcription or etanercept to inhibit TNFalpha activity significantly reduced TVX/LPS-induced liver injury. The results suggest that the model in mice is able to distinguish between drugs with and without the propensity to cause idiosyncratic liver injury and that the hepatotoxicity is dependent on TNFalpha.

Candin family antifungal agent micafungin (FK463) modulates the inflammatory cytokine production stimulated by lipopolysaccharide in THP-1 cells

Systemic inflammatory response syndrome (SIRS) and sepsis have been considered forms of hypercytokinemia in critically ill patients and immunocompromized hosts. It has been reported that some antimicrobial agents, including antifungal agents, not only have an antibiotic effect, but also they affect the host's immunological response. Immunofunctional cells, including monocytes and macrophages, were examined to determine whether they are influenced by the newly synthesized candin family antifungal agent micafungin (MCFG) using the human monocytic cell line THP-1 stimulated with lipopolysaccharide (LPS) as a model of hypercytokinetic conditions. LPS-induced production of TNF-alpha (tumor necrosis factor-alpha) and interleukin-8 (IL-8) in THP-1 cells was significantly suppressed dose-dependently by MCFG, although high concentrations of MCFG may reach toxic levels. It was clarified that MCFG inhibits the LPS-induced expression of TNF-alpha in THP-1 cells at the mRNA (messenger ribonucleic acid) level. In conclusion, administration of MCFG had an immunomodulatory effect on the host by reducing levels of TNF-alpha and IL-8. The effectiveness of MCFG in modulating hypercytokinemia is due not only to its direct antifungal effect, but also to the modulation of cytokine production in macrophages that regulates immunological activity and inflammation.

Effect of moxifloxacin on production of proinflammatory cytokines from human peripheral blood mononuclear cells

The effects of moxifloxacin, a new methoxyfluoroquinolone, on the production of proinflammatory cytokines from human peripheral blood mononuclear cells (PBMCs) were evaluated. Moxifloxacin inhibited the production of tumor necrosis factor alpha (TNF-alpha) and/or interleukin-6 (IL-6) by PBMCs stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), and heat-killed bacteria in a concentration-dependent manner without cytotoxic effects. The addition of moxifloxacin reduced the population of cells positive for CD-14 and TNF-alpha and for CD-14 and IL-6 among the LPS- or LTA-stimulated PBMCs. By Western blot analysis, moxifloxacin pretreatment reduced the degradation of IkappaBalpha in LPS-stimulated PBMCs. In conclusion, moxifloxacin could interfere with NF-kappaB activation by inhibiting the degradation of IkappaBalpha and reduce the levels of production of proinflammatory cytokines.

Modulation of polymorphonuclear cell interleukin-8 secretion by human monoclonal antibodies to type 8 pneumococcal capsular polysaccharide

Pneumococcal capsular polysaccharide (PS) vaccines induce type-specific immunoglobulin M (IgM), IgG, and IgA. Type-specific IgG to the PS is sufficient to confer protection against the homologous serotype of the pneumococcus, but the efficacies of type-specific IgM and IgA are less well understood. We examined the in vitro activities and efficacies in mice of two human monoclonal antibodies (MAbs) to type 8 PS, NAD (IgA) and D11 (IgM). MAb-mediated opsonophagocytic killing was evaluated after coculture of type 8 pneumococci with human polymorphonuclear cells (PMNs), type-specific or control MAbs, and human complement sources. The effects of the MAbs on PMN interleukin-8 (IL-8) and IL-6 secretion were determined in supernatants from cocultures containing pneumococci and PMNs by enzyme-linked immunosorbent assay. MAb efficacy was determined in an intratracheal model of type 8 infection in mice with classical complement pathway deficiency. Both MAbs were protective in 100% of infected mice. Neither MAb promoted a significant amount of killing of type 8 pneumococci compared to its isotype control MAb. Both type-specific MAbs mediated complement-dependent modulation of PMN IL-8 secretion, with increased secretion at effector/target (E:T) ratios of 500:1 and 50:1 and reduced secretion at 1:5. Trypan blue staining revealed that PMNs cocultured with D11 were less viable at an E:T ratio of 1:5 than PMNs cocultured with the control MAb. PMN IL-6 secretion was increased by both type-specific and control MAbs. These results suggest that certain type-specific IgM and IgAs might contribute to host defense by modulation of the inflammatory response to pneumococci.

Polymorphisms in lymphotoxin alpha and CD14 genes influence TNFalpha production induced by Gram-positive and Gram-negative bacteria

Improved understanding of how host genetic variation affects resistance to microbial pathogens could lead to better treatment and/or prevention of infectious diseases. The lymphotoxin alpha (LTA)+250 and CD14-159 polymorphisms are associated with differences in susceptibility or outcome to several infections. We stimulated peripheral blood mononuclear cells (PBMC) from 22 healthy individuals with purified lipopolysaccharide (LPS), heat-killed Escherichia coli or Streptococcus pneumoniae. TNF alpha intracellular protein levels were measured by flow cytometry and mRNA was quantitated by RT-PCR. TNF alpha mRNA levels were higher in LTA+250GG subjects after 4 h incubation with LPS compared with LTA+250AA (T test, P=0.001). In contrast, after 8 h incubation with S. pneumoniae, there was slightly more TNF alpha mRNA in cells from LTA+250AA subjects. After 4 h incubation with LPS or E. coli, CD14-159TT subjects had higher TNF alpha mRNA levels than CD14-159CC (P=0.05, 0.033, respectively). Neither polymorphism affected the proportion of cells expressing intracellular TNF alpha protein. This suggests that the polymorphisms affected transcription and that other regulatory mechanisms affect production of TNF alpha protein. The effect of these two polymorphisms on TNF alpha mRNA production is stimulus dependent, with opposite effects observed for Gram-positive and Gram-negative stimuli.

Immunomodulatory effects of quinolones

We review data on the in-vitro, ex-vivo, in-vivo, and clinical effects of fluoroquinolones on the synthesis of cytokines and their mechanisms of immunomodulation. In general, most fluoroquinolone derivatives superinduce in-vitro interleukin 2 synthesis but inhibit synthesis of interleukin 1 and tumour necrosis factor (TNF)alpha; furthermore, they enhance significantly the synthesis of colony-stimulating factors (CSF). Fluoroquinolones affect in-vivo cellular and humoral immunity by attenuating cytokine responses. Interleukins 10 and 12 have an important role in the functional differentiation of immunocompetent cells and trigger the initiation of the acquired immune response. In addition, certain fluoroquinolones were seen to enhance haematopoiesis by increasing the concentrations of CSF in the lung as well as in the bone marrow and shaft. Those fluoroquinolones exerting significant effects on haematopoiesis were those with a cyclopropyl moiety at position N1 of their quinolone core structure. Mechanisms that could explain the various immunomodulatory effects of fluoroquinolones include: (1) an effect on intracellular cyclic adenosine-3',5'-monophosphate and phosphodiesterases; (2) an effect on transcription factors such as nuclear factor (NF)kappaB, activator protein 1, NF-interleukin-6 and nuclear factor of activated T cells; and (3) a triggering effect on the eukaryotic equivalent of bacterial SOS response with its ensuing intracellular events. Further studies are required, especially in the clinical setting to exploit fully the potential of the immunomodulatory effect of fluoroquinolones during, for example, immunosuppression, chronic airway inflammatory diseases, and sinusitis.

In vitro effects of ciprofloxacin and roxithromycin on apoptosis of jurkat T lymphocytes

Ciprofloxacin (CPFX) and roxithromycin (RXM) induced apoptosis of activated Jurkat T cells in vitro. CPFX showed concentration-dependent acceleration of apoptosis of activated Jurkat T cells by enhancing the expression of FasL and activities of caspase-3 and -8. RXM accelerated cell death, enhanced expression of FasL and caspase-3 but not caspase-8, and did not show the concentration dependency.

Clindamycin modulates inflammatory-cytokine induction in lipopolysaccharide-stimulated mouse peritoneal macrophages

We investigated the mechanism by which clindamycin (CLI) modulates cytokine induction after lipopolysaccharide (LPS) stimulation. Although CLI decreased the intracellular expression levels of tumor necrosis factor alpha and interleukin 1beta (IL-1beta) and increased IL-6 expression in macrophages, cytokine mRNA expression levels were similar in CLI-treated and untreated groups. Our findings suggest that CLI modulates cytokine production in LPS-stimulated macrophages.

Cytokines in Lyme borreliosis: lack of early tumour necrosis factor-alpha and transforming growth factor-beta1 responses are associated with chronic neuroborreliosis

The clinical outcome of the tick born infection Lyme borreliosis seems to be influenced by the type of immune response mounted during the disease, as suggested by various animal models. Here we report the serum and cerebrospinal fluid levels of tumour necrosis factor-alpha (TNF-alpha), transforming growth factor beta1 (TGF-beta1) and interleukin-6 (IL-6) in samples drawn at different disease intervals during the course of non-chronic neuroborreliosis (n=10), chronic neuroborreliosis (n=15), erythema migrans (n=8, serum only) and controls (n=7). When comparing early neuroborreliosis cerebrospinal fluid samples, significantly higher levels of TNF-alpha were found in non-chronic patients than in chronic patients (P<0.05). Moreover, TGF-beta1 was increased in the early serum samples of non-chronic patients, as compared to chronic patients (P<0.01). Elevated serum levels of TGF-beta1 were also found in erythema migrans as compared to neuroborreliosis and controls (P<0.05). The high TNF-alpha levels noted in early cerebrospinal fluid samples of non-chronic patients only, possibly reflects an ongoing pro-inflammatory immune response in the central nervous system, which could be beneficial in eliminating disease. High serum levels of TGF-beta1 probably mirror an anti-inflammatory response, which might play a role in controlling the systemic immune response.

Immunomodulatory and protective effects of moxifloxacin against Candida albicans-induced bronchopneumonia in mice injected with cyclophosphamide

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.

Effects of antimicrobial agents on spontaneous and endotoxin-induced cytokine release of human peripheral blood mononuclear cells

Because the immunomodulatory effects of antibiotics could possibly influence the degree of the systemic and local response to infection, knowledge of their intrinsic influence on the host's inflammatory response appears to be essential. Therefore, this study investigated the effects of frequently used antimicrobial agents (beta-lactams, quinolones gentamicin, vancomycin and metronidazole) on the in-vitro tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 production of isolated human peripheral blood mononuclear cells (PBMNC), cultured with or without endotoxin, in comparison with those effects obtained in a whole-blood assay system. In the presence of ciprofloxacin, ofloxacin, gentamicin, vancomycin, and metronidazole, a significant inhibition of the endotoxin-stimulated TNF-alpha production of human peripheral blood mononuclear cells (PBMNC) was found at therapeutic levels. Only ofloxacin showed a significant inhibitory influence on the endotoxin-induced IL-6 production of PBMNC. In the whole-blood assay, significant effects were not detectable. None of the antibiotics showed cytotoxicity. It is concluded that, at present, the direct immunological effects of antibiotics should be interpreted carefully with regard to the experimental conditions, and regardless of the therapeutic implications. To assess the potential direct immunomodulatory effect of antimicrobial agents, different cell culture procedures should be used.