Mimicking Nonribosomal Peptides from the Marine Actinomycete Streptomyces sp. H-KF8 Leads to Antimicrobial Peptides

Microorganisms within the marine environment have been shown to be very effective sources of naturally produced antimicrobial peptides (AMPs). Several nonribosomal peptides were identified based on genome mining predictions of Streptomyces sp. H-KF8, a marine Actinomycetota isolated from a remote Northern Chilean Patagonian fjord. Based on these predictions, a series of eight peptides, including cyclic peptides, were designed and chemically synthesized. Six of these peptides showed antimicrobial activity. Mode of action studies suggest that two of these peptides potentially act on the cell membrane via a novel mechanism allowing the passage of small ions, resulting in the dissipation of the membrane potential. This study shows that though structurally similar peptides, determined by NMR spectroscopy, the incorporation of small sequence mutations results in a dramatic influence on their bioactivity including mode of action. The qualified hit sequence can serve as a basis for more potent AMPs in future studies.

Significant and rapid reduction of free endotoxin using a dialkylcarbamoyl chloride-coated wound dressing

OBJECTIVE

Endotoxin causes inflammation and can impair wound healing. Conventional methods that reduce bioburden in wounds by killing microorganisms using antibiotics, topical antimicrobials or antimicrobial dressings may induce endotoxin release from Gram-negative bacteria. Another approach is to reduce bioburden by adsorbing microorganisms, without killing them, using dialkylcarbamoyl chloride (DACC)-coated wound dressings. This study evaluated the endotoxin-binding ability of a DACC-coated wound dressing (Sorbact Compress, Abigo Medical AB, Sweden) in vitro, including its effect on the level of natural endotoxin released from Gram-negative bacteria.

METHOD

Different concentrations of purified Pseudomonas aeruginosa endotoxin and a DACC-coated dressing were incubated at 37°C for various durations. After incubation, the dressing was removed and endotoxin concentration in the solution was quantified using a Limulus amebocyte lysate (LAL) assay. The DACC-coated dressing was also incubated with Pseudomonas aeruginosa cells for one hour at 37°C. After incubation, the dressing and bacterial cells were removed and shed endotoxin remaining in the solution was quantified.

RESULTS

Overnight incubation of the DACC-coated wound dressing with various concentrations of purified Pseudomonas aeruginosa endotoxin (96-11000 EU/ml) consistently and significantly reduced levels of free endotoxin by 93-99% (p<0.0001). A significant endotoxin reduction of 39% (p<0.001) was observed after five minutes. The DACC-coated dressing incubated with clinically relevant Pseudomonas aeruginosa cells also reduced shed endotoxin by >99.95% (p<0.0001).

CONCLUSION

In this study, we showed that a DACC-coated wound dressing efficiently and rapidly binds both purified and shed endotoxin from Pseudomonas aeruginosa in vitro. This ability to remove both endotoxin and bacterial cells could promote the wound healing process.

Endotoxin in Aerosol Particles from Metalworking Fluids Measured with a Sioutas Cascade Impactor

OBJECTIVES

The aim of this study was to characterize personal occupational exposure to endotoxin in size-separated airborne particles of MWF aerosol, using a Sioutas cascade impactor (SCI).

METHODS

Exposure to inhalable fractions of MWF aerosol and endotoxin was measured by personal sampling of 52 individuals over an 8-h work shift using a PAS-6 sampler in parallel with a SCI (<0.25, 0.25-0.5, 0.5-1.0, 1.0-2.5, and 2.5-10 µm). Aerosol mass concentration was measured for each worker with a real-time instrument (DataRAM) during a full shift. Samples of MWF were collected from the machines and central tanks during the work shift.

RESULTS

A total of 117 measurements of inhalable MWF aerosols were made among 52 workers. The geometric mean of inhalable MWF aerosol was 0.16 mg m-3 air. The geometric mean of endotoxin concentration on the inhalable sampler was 0.15 EU m-3. Airborne endotoxin was found on all size fractions from the impactor, with the major part seen in the fraction (2.5-10 µm). There was a correlation between the inhalable fraction of endotoxin measured by the PAS-6 sampler and on the SCI sampler (2.5-10 µm), estimated to be 0.51 for all samples (P < 0.0001). The concentration of endotoxin varied between the MWFs, as did the proportion of Gram-negative bacteria among the culturable bacteria (>80% in one MWF and <1.5% in the other three).

CONCLUSIONS

The personal exposure to inhalable fractions of endotoxin contained in the MWF aerosol were low, where most of the endotoxin were found in fraction (2.5-10 µm), measured by SCI. There are differences between factories and MWF systems regarding the distribution of endotoxin and so results from one context should not be generalized to other plants and systems. Compressed air was used for less than 10 min shift-1. The mixed-effect model showed that working with open machines and grinding as cutting task were important determinants of exposure to inhalable aerosol. It is important to keep occupational exposure to aerosols low with the help of good ventilation systems, enclosed machines, and organization of work.

Anti-infective efficacy of the lactoferrin-derived antimicrobial peptide HLR1r

Antimicrobial peptides (AMPs) have emerged as a new class of drug candidates for the treatment of infectious diseases. Here we describe a novel AMP, HLR1r, which is structurally derived from the human milk protein lactoferrin and demonstrates a broad spectrum microbicidal action in vitro. The minimum concentration of HLR1r needed for killing ≥99% of microorganisms in vitro, was in the range of 3-50μg/ml for common Gram-negative and Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), and for the yeast Candida albicans, when assessed in diluted brain-heart infusion medium. We found that HLR1r also possesses anti-inflammatory properties as evidenced by inhibition of tumor necrosis factor alpha (TNF-α) secretion from human monocyte-derived macrophages and by repression of interleukin-6 (IL-6) and plasminogen activator inhibitor-1 (PAI-1) secretion from human mesothelial cells, without any cytotoxic effect observed at the concentration range tested (up to 400μg/ml). HLR1r demonstrated pronounced anti-infectious effect in in vivo experimental models of cutaneous candidiasis in mice and of excision wounds infected with MRSA in rats as well as in an ex vivo model of pig skin infected with S. aureus. In conclusion, HLR1r may constitute a new therapeutic alternative for local treatment of skin infections.

Endotoxin in Size-Separated Metal Working Fluid Aerosol Particles

Patients with airway symptoms working in metal working industries are increasing, despite efforts to improve the environmental air surrounding the machines. Our aim was to analyse the amount of endotoxin in size-separated airborne particles of metal working fluid (MWF) aerosol, by using the personal sampler Sioutas cascade impactor, to compare filter types, and to compare the concentration of airborne endotoxin to that of the corresponding MWFs. In a pilot field study, aerosols were collected in two separate machine halls on totally 10 occasions, using glass fibre and polytetrafluoroethylene (PTFE) filters in parallel at each station. Airborne endotoxin was distributed over all size fractions. While a major part was found in the largest size fraction (72%, 2.5-10 µm), up to 8% of the airborne endotoxin was detected in the smallest size fraction (<0.25 µm). Comparing the efficiency of the filter types, a significantly higher median endotoxin level was found with glass fibres filters collecting the largest particle-size fraction (1.2-fold) and with PTFE filters collecting the smallest ones (5-fold). The levels of endotoxin in the size-separated airborne particle fractions correlated to those of the MWFs supporting the aerosol-generating machines. Our study indicates that a significant part of inhalable aerosols of MWFs consists of endotoxin-containing particles below the size of intact bacteria, and thus small enough to readily reach the deepest part of the lung. Combined with other chemical irritants of the MWF, exposure to MWF aerosols containing endotoxin pose a risk to respiratory health problems.

IgG1 anti-cell wall and IgG2 anti-phosphopeptidomannan antibodies in the diagnosis of invasive candidiasis and heavy Candida colonization

We conducted a retrospective study to evaluate the usefulness of immunoglobulin G (IgG) subclasses against Candida cell wall fragments (CW) and phosphopeptidomannan (PPM) for the diagnosis of invasive candidiasis (IC). We analyzed 54 patients with IC (n = 19), Candida heavy colonization (HC; n = 16), and controls (no IC or HC, n = 19).In nonneutropenic patients (n = 47), the sensitivity and specificity values of IgG1 anti-CW and IgG2 anti-PPM in IC were 88%, 59%, and 88%, 94%, respectively. The areas under the receiver operating characteristic curves were 0.69 (0.51-0.88) and 0.901 (0.78-1.02), respectively. IgG1 mean values (arbitrary units) and 95% confidence interval were 46 (20-71), 42 (-0.38 to 84) and 20 (8.3-32) in IC, HC, and in controls, respectively, and discriminated IC but not HC from controls (P = .032, and P = .77, respectively). IgG2 mean values were 26 (9.2-42), 19 (4.4-33), and 3.2 (0.28-6.6) in IC, HC, and in controls, respectively, and discriminated both IC and HC from controls (P < .0001 and P = .035, respectively) but did not separate IC from HC (P = .2). IgG2 showed positivity as early as one day after the IC diagnosis. Antibodies were detected in only two out of a total of seven neutropenic patients.For both IC and HC patients, the diagnostic performance of IgG2 anti-PPM was better than the one of IgG1 anti-CW. In nonneutropenic patients, IgG2 anti-PPM accurately identified not only IC patients but also HC patients at high risk for IC. This marker may help clinicians in the initiation of early preemptive therapy.

Immunological aspects of pyelonephritis

Several virulence factors, such as O and K antigens and capacity to attach to uroepithelial cells, seem to be required for Escheria coli to cause acute pyelonephritis. These factors induce an immune response, however, which can modify the course and clinical expression of the infection. During acute pyelonephritis, autoantibodies to the Tamm-Horsfall protein increase. These antibodies, which probably are evoked by a cross-reaction noted between structures of E. coli LPS and the Tamm-Horsfall protein, may add to the renal tissue engagement in interstitial nephritis caused by bacterial pyelonephritis.

Endocytosis and trafficking of human lactoferrin in macrophage-like human THP-1 cells1This article is part of a Special Issue entitled Lactoferrin and has undergone the Journal’s usual peer review process

Different cell types have been reported to internalize lactoferrin (Lf) by specific or nonspecific receptors. Our studies focused on the endocytic pathway of human Lf in macrophage-like THP-1 cells. Lactoferrin was found to be internalized by THP-1 cells differentiated with phorbol myristate acetate. Incubation of cells with chlorpromazine and dansylcadaverine, inhibitors of clathrin-dependent endocytosis, led to a 50% inhibition of Lf internalization compared with untreated cells. Bafilomycin A1 and NH4Cl treatment also resulted in 40%–60% inhibition, respectively, suggesting that the internalization of Lf may partly be mediated by acidic endosome-like organelles. Endocytic uptake of Lf was also cholesterol-dependent, as shown by methyl-β-cyclodextrin or nystatin treatment of the cells prior to internalization. Partial colocalization of Lf and EEA-1, a marker specific for early endosomes, could be observed. Colocalization of Lf with a specific endoplasmic reticulum marker was also detected. Our results suggest that Lf is internalized mainly by the clathrin-dependent pathway in THP-1 cells and targets the ER. The physiological consequences of this intracellular trafficking will be the subject of future investigations.

Affinity apheresis for treatment of bacteremia caused by Staphylococcus aureus and/or methicillin-resistant S. aureus (MRSA)

Staphylococcus aureus (SA) bacteremia is associated with high mortality, and often results in metastatic infections. The methicillin-resistant SA (MRSA) is an urgent health care issue, as nosocomial infections with these bacteria represent limited treatment alternatives. Samples of whole blood containing challenge inoculums of SA and MRSA strains were passed through columns packed with surface-heparinized polyethylene beads. The bound bacteria were eluted and quantitatively determined by culturing and by real-time PCR. Significant amounts of both SA and MRSA adhered to the heparinized beads (more than 65% of inoculated bacteria). After rinsing with buffer at high ionic strength, viable bacteria or bacterial DNA were eluted from the columns, indicating that the binding was specific. The conclusions that can be made from these experiments are that, as earlier reported in the literature, the high affinity of SA to heparin is retained in whole blood, and MRSA in whole blood binds to heparin with similar or higher affinity than SA. It should be possible to lower the amount of SA and/or MRSA from the blood of infected patients to levels that could be taken care of by the immune system. In previous studies, we have shown that passing blood from septic patients over beads coated with end-point-attached, biologically active heparin is a useful technique for regulating the levels of heparin-binding cytokine. These findings in combination with the present findings indicate the possibility of creating an apheresis technology for treatment of sepsis caused by SA and/or MRSA.

In vitro susceptibility of filamentous fungi to itraconazole, voriconazole and posaconazole by Clinical and Laboratory Standards Institute reference method and E-test

The use of anti-fungal agents has increased dramatically in recent years and new drugs have been developed. Several methods are available for determinations of their specific biological activities, i.e. the standard method for minimum inhibitory concentration-determination is described in M-38 [Clinical and Laboratory Standards Institute document M-38 (CLSI M-38)]. However, alternative methods, such as the E-test, are currently available in Mycology laboratories. The susceptibilities of clinical isolates of Aspergillus spp. (n = 29), Fusarium spp. (n = 5), zygomycetes (n = 21) and Schizophyllum (n = 1) were determined for itraconazole, voriconazole and posaconazole, using the CLSI M-38-A broth dilution method and also by the E-test. A good overall agreement (83.7%) between the two methods for all drugs and organisms was observed. Analyses of voriconazole showed a better agreement (93%) between the methods than posaconazole and itraconazole (85% and 74% respectively). Aspergillus spp. were the most susceptible fungi to the anti-fungal agents tested in this study. Posaconazole was the most active drug against filamentous fungi in vitro, followed by itraconazole and voriconazole. The latter (voriconazole) demonstrated no significant in vitro activity against zygomycetes.

A novel monoclonal antibody recognizing beta(1-3) glucans in intact cells of Candida and Cryptococcus

The cell walls of all medically important fungi contain a unique polyglucose compound, beta(1-3) glucan. In the present study, murine monoclonal antibodies were produced against linear and beta(1-6) branched beta(1-3) glucans, and their specificities were characterized for reactivity to other beta glucans, fungal cell wall fragments, and fungal cells. Their reactivity was also compared with that of rabbit polyclonal antibodies raised against the same immunogens. Two mouse monoclonal antibodies (AG and BG) recognized immunoreactive epitopes in beta(1-3)(1-6) glucan by ELISA. In an inhibition assay of the anti-beta(1-3)(1-6) activity of the monoclonals, the homologous antigen effectively inhibited the activity as expected, while beta(1-3) also inhibited the assay but to a much lesser extent. No inhibition was obtained by beta(1-3)(1-4) or beta(1-6), while a cell wall extract of Candida albicans (PPM) effectively inhibited both monoclonals. Cell wall fragments of C. albicans (CaCW) and Cryptococcus neoformans (CnCW) inhibited the anti-beta(1-3)(1-6) activity of AG, while BG was much less or not inhibited at all. Immunofluorescence confirmed the unique antibody specificity of AG by its recognition of a beta(1-3)(1-6)-associated epitope on the cell surfaces of C. albicans,C. krusei, C. glabrata, and nonencapsulated C. neoformans. The epitope for the AG antibody is suggested to be present in the branching point of beta(1-3)(1-6), or in the randomly coiled beta(1-3) polyglucan due to the presence of branches. Thus, monoclonal antibodies to beta(1-3)(1-6) glucans may have potential as tools in the laboratory diagnosis of invasive yeast infections.

Growth and nutrition: the first six months

Today the WHO Growth Chart Standards, based on the growth of breastfed infants, are used. These growth curves solve the problem of the deviating observations for breastfed compared to non-breastfed infants using previous growth charts. Presently it is not clear how the mother's diet, especially the fat intake, influences the growth of the offspring. Animal experiments indicate that a low intake of n-3 polyunsaturated fatty acids via the milk may have short- and long-term negative consequences. There is limited information in man. It has been suggested that the mammary glands may have phylogenetically originated from glands providing innate immunity, later developing capacities for providing nutrition. This would agree with the fact that human milk contains so many major components which do not primarily function as nutrients, but seem to protect nutrition and growth. Lactoferrin, oligosaccharides, glycoproteins, secretory IgA antibodies, alpha-lactalbumin and the antisecretory factor have such functions.

Prevotella bivia can invade human cervix epithelial (HeLa) cells

Prevotella bivia has been associated with female upper genital tract infections and an increased risk of preterm delivery. In this study, the adherence and invasion capacity of P. bivia was investigated using a cervix epithelial cell line. P. bivia was furthermore analysed for its ability to evoke a proinflammatory cytokine response in epithelial cells. The invasion capacity, defined as the number of bacteria recovered from lysed HeLa cells infected with P. bivia, varied considerably among five strains, all of which were isolates from women with bacterial vaginosis. One P. bivia strain (P47) gave rise to an approximately 120-fold higher number of intracellular bacteria (7 x 10(3) bacteria per 1 x 10(5) cells) compared with the least invasive strain. Three strains expressed an intermediate or low invasiveness, showing an approximately 3- to 40-fold higher number of intracellular bacteria per 1 x 10(5) cells compared with the least invasive strain. The intracellular localization of P47 in phagosome-like vesicles was confirmed by transmission electron microscopy. All P. bivia strains adhered to HeLa cells to the same extent (range 14-22 bacteria per cell) as analysed by interference microscopy. No correlation was found between adhesion and invasion capacity of the strains. Furthermore, no fimbriae-like structures were observed on P47 detected by scanning electron microscopy or negative staining. Analysis of TNF-alpha, IL-1alpha, IL-6, IL-8, and IL-18 in P. bivia-stimulated HeLa cells showed low levels of only IL-6 and IL-8 for the most invasive P. bivia strain P47. Thus, the induction of IL-6 or IL-8 secretion appeared to be associated with invasion capacity. This work provides evidence that some P. bivia isolates can invade human cervix epithelial. Thus, a strong capacity for invasion and a weak proinflammatory cytokine-inducing capacity in P. bivia are suggested to be virulence factors in establishing a low-grade upper genital tract infection.

Interleukin-6 and interleukin-8 in cervical and amniotic fluid: relationship to microbial invasion of the chorioamniotic membranes

OBJECTIVE

To evaluate the levels of interleukin (IL)-6 and IL-8 in cervical and amniotic fluid in relation to the presence of bacteria in the membranes in women in preterm labour (PTL).

DESIGN

A prospective follow up study.

SETTING

Sahlgrenska University Hospital, Göteborg, Sweden. Sample Women with singleton pregnancies (<34 weeks) presenting with PTL (n = 30).

METHODS

Amniotic fluid was retrieved transabdominally and cervical fluid was sampled from the uterine cervix at admission and analysed for IL-6 and IL-8 with enzyme-linked immunosorbent assay (ELISA). At birth, the chorioamniotic membranes were separated and samples for polymerase chain reaction (PCR) for Ureaplasma urealyticum and Mycoplasma hominis and general culture were obtained.

MAIN OUTCOME MEASURE

IL-6 and IL-8 in relation to microbial invasion of the chorioamniotic membranes.

RESULTS

Bacteria were found in the membranes in 8 of 21 patients in PTL for whom chorioamnion as well as amniotic fluid PCR and cultures were available. Cervical IL-6 was associated with detectable bacteria in the chorioamniotic membranes in women in PTL (median 8.2 ng/mL vs 0.73 ng/mL; P = 0.01). The IL-6 (median 13 ng/mL vs 1.7 ng/mL; P = 0.004) and IL-8 (median 7.2 ng/mL vs 0.28 ng/mL; P = 0.01) levels in amniotic fluid were higher in PTL cases in which bacteria were found in the chorioamniotic membranes.

CONCLUSION

IL-6 in cervical fluid and IL-6 and IL-8 in amniotic fluid were higher in those PTL cases in which bacteria were found in the chorioamniotic membranes.

Interleukin-6 and interleukin-8 in cervical fluid in a population of Swedish women in preterm labor: relationship to microbial invasion of the amniotic fluid, intra-amniotic inflammation, and preterm delivery

BACKGROUND

Intrauterine infection and inflammation in women with preterm labor are related to adverse perinatal outcome. Due to its subclinical nature, a correct diagnosis depends on retrieval of amniotic fluid. Amniocentesis is, however, not performed as a clinical routine because of its invasiveness. Hypothetically, cytokines in the cervical fluid may represent an alternative diagnostic approach. The aim was to examine cervical interleukin (IL)-6 and IL-8 in relation to microbial invasion of the amniotic fluid, intra-amniotic inflammation, and preterm birth in women in preterm labor.

METHODS

Women with singleton pregnancies in preterm labor (<34 weeks of gestation) and intact membranes were included. Cervical (n = 91) and amniotic fluids (n = 56) were collected. Polymerase chain reaction for Ureaplasma urealyticum and Mycoplasma hominis and culture for aerobic and anaerobic bacteria were performed. IL-6 and IL-8 were analyzed with enzyme-linked immunosorbent assay.

RESULTS

Non-lactobacillus-dominated biota was detected in cervical secretion in 25% (22/89) and the presence of micro-organisms in the amniotic fluid in 16% (9/56) of the patients. The presence of U. urealyticum in the cervical fluid (21/46) was associated with significantly higher levels of IL-6 in the secretion. IL-6 and IL-8 were significantly higher in cervical fluid of women with intra-amniotic infection and inflammation and in women who delivered < or =7 days and/or before 34 weeks of gestation. Cervical IL-6 > or = 1.7 ng/ml was related to intra-amniotic inflammation (relative risk: 2.67; range: 1.50-4.74) and had a sensitivity, specificity, positive predictive value, and negative predictive value of 58, 83, 75, and 69%, respectively, in the identification of intra-amniotic inflammation. Similar data were obtained for IL-8 > or = 6.7 ng/ml.

CONCLUSIONS

High levels of cervical IL-6 and IL-8 are moderately predictive of intrauterine infection/inflammation and preterm delivery.

Bacterial vaginosis - a microbiological and immunological enigma. Review article

The development of bacterial vaginosis (BV) among women of childbearing age and the resulting quantitative and qualitative shift from normally occurring lactobacilli in the vagina to a mixture of mainly anaerobic bacteria is a microbiological and immunological enigma that so far has precluded the formulation of a unifying generally accepted theory on the aetiology and clinical course of BV. This critical review highlights some of the more important aspects of BV research that could help in formulating new basic ideas respecting the biology of BV, not least the importance of the interleukin mediators of local inflammatory responses and the bacterial shift from the normally occurring lactobacilli species: L. crispatus, L. gasseri, L. jensenii, and L. iners to a mixed flora dominated by anaerobic bacteria.

Circulating beta (1-3) glucan and immunoglobulin G subclass antibodies to Candida albicans cell wall antigens in patients with systemic candidiasis

Invasive candidiasis in patients who are immunocompromised or in intensive care units (ICUs) presents both diagnostic and therapeutic problems. We previously described antibodies that were directed against Candida albicans cell wall fragments (CW), periodate-treated CW (CW(IO4)), phosphopeptidomannan (PPM), and beta(1-3) glucan. In this study, circulating fungal antigens [mannan and beta(1-3) glucan] and immunoglobulin G (IgG) subclass antibodies to these cell wall antigens (anti-CW) were analyzed in patients with systemic candidiasis. Sera were collected from 14 patients on two or three consecutive occasions, starting on the day when candidiasis was culture proven. The sera were analyzed by enzyme-linked immunosorbent assay. The control groups consisted of lactating mothers (n = 9) (group I) who had breast milk that was positive for C. albicans and also had acute inflammation of the nipples, and age-matched blood donors (n = 10) (group II). Within the first 3 weeks of Candida infection all of the patients were positive for beta(1-3) glucan by the Gluspecy test, but no patients were positive for mannan in the less-sensitive Pastorex Candida test. The controls were negative for both beta(1-3) glucan (<20 pg/ml) and mannan (<2.5 ng/ml). IgG1 anti-CW and IgG2 anti-PPM antibodies were the most discriminatory antibodies. The ratio of IgG1 anti-CW to IgG2 anti-PPM was significantly lower in nonsurviving patients than in the other patients within the first week of candidiasis (P = 0.019). The IgG2 levels of anti-CW(IO4) and antiglucan antibodies correlated strongly (r = 0.681; P < 0.0001), and the absence of these antibodies was associated with increased levels of beta(1-3) glucan. Increased levels of IgG1 anti-CW or IgG2 anti-PPM antibodies (titer of > or = 3 logs) or of a combination of the two antibodies (log sum, > or = 5) showed 92% sensitivity, 100% specificity, and positive predictive values. In conclusion, beta(1-3) glucan and the two subclass antibodies appear to be early specific markers for the laboratory diagnosis of candidiasis. Furthermore, the kinetics of beta(1-3) glucan appearance in serum may assist in evaluating the therapeutic efficacy of antifungal treatments.

Interleukin-18 in cervical mucus and amniotic fluid: relationship to microbial invasion of the amniotic fluid, intra-amniotic inflammation and preterm delivery

OBJECTIVE

To evaluate the relationship between interleukin (IL)-18 in cervical mucus and amniotic fluid and microbial invasion of amniotic fluid, preterm delivery and intra-amniotic inflammation in women in preterm labour, with preterm prelabour rupture of membranes and at term.

DESIGN

A prospective follow up study.

SETTING

Sahlgrenska University Hospital, Göteborg, Sweden.

SAMPLE

Women with singleton pregnancies (<34 weeks) presenting with preterm labour (n = 87) or preterm prelabour rupture of membranes (n = 47) and women, not in labour, at term (n = 28).

METHODS

Amniotic fluid was retrieved transabdominally. Cervical mucus was taken from the uterine cervix of women in preterm labour and at term. IL-18 was analysed with enzyme-linked immunosorbent assay.

MAIN OUTCOME MEASURES

IL-18 in relation to microbial invasion of the amniotic fluid, delivery within seven days or <34 weeks of gestation and intra-amniotic inflammation.

RESULTS

The levels of IL-18 in cervical mucus and amniotic fluid were higher in women with preterm labour than in those not in labour at term. In the preterm labour group, significant associations were found between elevated IL-18 in amniotic fluid and microbial invasion of the amniotic fluid, as well as between delivery within seven days or <34 weeks of gestation and intra-amniotic inflammation. Delivery was delayed longer in the preterm prelabour rupture of membranes subgroup with IL-18 >or=1.0 ng/mL than in that with IL-18 <1.0 ng/mL.

CONCLUSIONS

In the preterm labour group, high IL-18 in amniotic fluid (but not in the cervix) was associated with microbial invasion of the amniotic fluid, intra-amniotic inflammation and prompt delivery. On the other hand, elevated IL-18 in preterm prelabour rupture of the membranes group correlated with a longer interval to delivery.

Microbial invasion and cytokine response in amniotic fluid in a Swedish population of women with preterm prelabor rupture of membranes

BACKGROUND

Previous studies have shown an association between intra-amniotic microbial invasion and/or inflammation and spontaneous preterm birth. The aim of this study was to investigate the occurrence of intra-amniotic microorganisms and cytokines [interleukin (IL)-6 and IL-8] in a Swedish population, with low incidence of preterm birth, of women with preterm prelabor rupture of membranes and their correlation to preterm birth.

METHODS

Amniotic fluid was retrieved transabdominally from 58 patients with preterm prelabor rupture of membranes before 34 weeks of gestation. Polymerase chain reaction (PCR) analyses for Ureaplasma urealyticum and Mycoplasma hominis and culture for aerobic and anaerobic bacteria were performed. IL-6 and IL-8 were analyzed with enzyme-linked immunosorbent assay (ELISA).

RESULTS

Microorganisms in amniotic fluid were detected in 13 patients (25%). Patients with bacteria detected in the amniotic fluid had significantly higher levels of IL-6 and IL-8. An amniotic fluid concentration of IL-6 >/= 0.80 ng/ml [relative risk 1.93, 95% confidence interval (CI) 1.13-3.29, sensitivity 63%, specificity 75%] was associated with an increased risk of delivery within 7 days. There was also an association between IL-8 and preterm birth (< 34 weeks).

CONCLUSIONS

Intra-amniotic microbial invasion and inflammation in this population of Swedish women with preterm prelabor rupture of membranes were similar to data reported from populations with a higher incidence of preterm delivery. Amniotic IL-6 correlated to the presence of microorganisms and delivery within 7 days and IL-8 to delivery before 34 weeks.

The transfer of immunity from mother to child

The newborn's immune system grows fast from a small size at birth by exposure primarily to the intestinal microflora normally obtained from the mother at and after birth. While building up its immune system, the infant is supported by the transplacental IgG antibodies, which also contain anti-idiotypic antibodies, possibly also actively priming the offspring. The second mode of transfer of immunity occurs via the milk. Numerous major protective components, including secretory IgA (SIgA) antibodies and lactoferrin, are present. The breastfed infant is better protected against numerous common infections than the non-breastfed. Breastfeeding also seems to actively stimulate the infant's immune system by anti-idiotypes, uptake of milk lymphocytes, cytokines, etc. Therefore, the breastfed child continues to be better protected against various infections for some years. Vaccine responses are also often enhanced in breastfed infants. Long-lasting protection against certain immunological diseases such as allergies and celiac disease is also noted.

Candida albicans cell wall antigens for serological diagnosis of candidemia

Serological tests for diagnosis of disseminated fungal infections in the immunocompromised host are used with varying results. In the present study, the relative ability of antibodies to specifically recognize Candida albicans cell wall components was evaluated in order to find antigenic markers for serological diagnosis of candidemia. Native C. albicans cell wall fragments (CW), periodate- (CWIO4) and proteinase-K- (CWP) treated CW, a mildly extracted phosphopeptidomannan (PPM), and beta(1-3)(1-6)-glucan were used as antigens in ELISA with sera from rabbits immunized with C. albicans (n = 10), patients with culture proven candidemia (n = 8) and healthy individuals (n = 8). The antibody response in rabbits consisted predominantly of anti-PPM antibodies, a finding that was substantiated by inhibition-ELISA. Consistently, periodate treatment (CW104) destroyed a major proportion of the antigenic epitopes. Low rabbit antibody levels were found against glucan, the major Candida cell wall component. These results supported the conclusion that glucan is localized mainly in the inner part of the C. albicans cell wall. In contrast to rabbits' serum IgG antibody response against PPM, which was at least tenfold higher than that raised against CW, patients with candidemia had similar IgG antibody levels against both antigens. These levels were significantly higher than those seen in healthy controls (CW, P = 0.0005 and PPM, P < 0.0001). Although the human anti-glucan and anti-CWIO4 IgG antibody levels were low overall, they were nonetheless significantly increased in the patient group (P = 0.0159 for antiglucan and P = 0.0491 for anti-CWIO4). In addition, a correlation was noticed between levels of these antibodies. No significant differences were found between patients and controls for IgM antibodies when CW, CWIO4, PPM and Glu were used as antigens. In conclusion, IgG antibodies to PPM and native cell wall fragments (CW) were highly discriminatory for recognition of candidemia and these antigens are thus promising candidates for use in serodiagnosis.

Microbial invasion and cytokine response in amniotic fluid in a Swedish population of women in preterm labor

BACKGROUND

Previous studies indicate an association between intra-amniotic microbial invasion and/or inflammation and spontaneous preterm birth, but there is a limited amount of data available from Europe. The aim of this study was to investigate the occurrence of intra-amniotic microorganisms and cytokines (interleukin-6 and interleukin-8) in a Swedish population of women in preterm labor and their correlation with preterm birth.

METHODS

Amniotic fluid was retrieved transabdominally from 61 patients in preterm labor before 34 weeks of gestation. Polymerase chain reaction analyses for Ureaplasma urealyticum and Mycoplasma hominis and culture for aerobic and anaerobic bacteria were performed. Interleukin-6 and interleukin-8 were analyzed with enzyme-linked immunosorbent assay.

RESULTS

Microorganisms in amniotic fluid were detected in 10 patients (16%). Patients with detected bacteria in the amniotic fluid had significantly higher levels of interleukin-6 and interleukin-8. There was also an association between interleukin-6/-8, the amniocentesis-delivery interval (<or= 7 days) and preterm birth (<34 weeks). An amniotic fluid concentration of interleukin-6 >or= 1.5 ng/mL or interleukin-8 >or= 1.3 ng/mL was associated with an increased risk of delivery within 7 days (interleukin-6: relative risk 7.3; 95% confidence interval: 2.8-19; sensitivity 83%, specificity 87%; interleukin-8: relative risk 14, 95% confidence interval: 3.6-55, sensitivity 91%, specificity 87%).

CONCLUSIONS

The occurrence of intra-amniotic microbial invasion and inflammation in this population of Swedish women in preterm labor was similar to data reported from populations with a higher incidence of preterm delivery. Amniotic interleukin-6 and interleukin-8 correlated with the presence of microorganisms and with preterm birth.

Anti-inflammatory activities of human lactoferrin in acute dextran sulphate-induced colitis in mice

In this study, we investigated the anti-inflammatory effects of orally administered human lactoferrin (hLF) and two peptides, based on the bactericidal region of hLF (HLD1 and HLD2), on the course of experimental colitis. Acute colitis was induced in C57Bl/6 mice by giving 5% dextran sulphate (DX) in the drinking water. The mice were killed after 2 or 7 days of DX exposure. The animals were given hLF or the peptides orally twice a day (2 mg/dose/mouse) during the DX exposure. In the control animals, the hLF or the peptides were replaced by bovine serum albumin or water. The appearance of occult blood in the faeces and macroscopic rectal bleeding were significantly delayed and partly reduced in the hLF-treated animals compared with the control animals. The shortening of the colon, a pathological effect of DX exposure, was significantly less pronounced in the hLF-treated group compared with the control group. Also, the interleukin-1beta (IL-1beta) levels in the blood were significantly diminished in this group after 2 days of DX exposure. A significantly lower crypt score was observed in the distal part of the colon in the hLF-treated group compared with the control group. Also, significantly reduced numbers of CD4 cells, F4/80-positive macrophages and tumour necrosis factor-alpha-producing cells were detected by immunohistochemistry in the distal colon of the hLF-treated animals compared with the control animals after 7 days of DX exposure. A reduction was also observed concerning the IL-10-producing cells in the middle colonic submucosa. The HLD1 and HLD2 treatment, which was carried out for 2 days, only gave results almost identical to those of hLF, concerning clinical parameters after the 2 days of DX exposure. An even stronger effect was observed for HLD2, regarding decreased occult blood in the faeces and colon length. Our results show that perorally given hLF mediates anti-inflammatory effects on the DX-induced acute colitis, and further suggest that the bactericidal region of the hLF molecule may be involved in these activities.

Lactoferrin down-regulates the LPS-induced cytokine production in monocytic cells via NF-kappa B

Lactoferrin, a glycoprotein present in milk, mucosal secretions and neutrophils contributes to host defense. We have previously shown that orally given milk lactoferrin (LF) mediates anti-infectious and anti-inflammatory activities in vivo. Moreover, we have shown that LF could inhibit the LPS-induced IL-6 secretion in a human monocytic cell line, THP-1. This observation was expanded in the present study investigating the capacity of LF to inhibit cytokine mRNA expression and the involvement of nuclear transcription factor kappa B (NF-kappa B). Cells (THP-1 and Mono Mac 6 monocytic cell lines) were stimulated with Escherichia coli LPS (5-10 ng/10(6) cells) and LF was added (50-500 microg/10(6) cells) 30 min before, or after the LPS addition. By a semiquantitative RT-PCR lower levels of TNF-alpha, IL-1 beta, IL-6, and IL-8 mRNA expression were detected at the peak of the expression in THP-1 cells treated with LF. The reduction in the cytokine expression was followed by a similar reduction in the secreted cytokines as analyzed by ELISA. LF down-regulated also the IL-10 secretion (detected only in LPS-stimulated Mono Mac 6 cells). A similar level of inhibition of these cytokines was detected regardless of the time at which LF was added to the cells in relation to LPS. In addition, LF was internalized into cells and detected in the nucleoli as determined by immunostaining and immunofluorescence. Moreover, by electrophoretic mobility shift assay (EMSA) analysis LF decreased the LPS-induced binding of NF-kappa B to the TNF-alpha promoter. The results show that LF down-regulates the LPS-induced cytokine production in monocytic cells. The inhibitory mechanism is suggested to involve the interference of LF with NF-kappa B activation.

Breast-feeding, a complex support system for the offspring

The newborn has an immune system, very limited in size at birth and its postnatal expansion and maturation takes time. In the meantime the transplacental IgG antibodies from the mother play an important role for the protection of the infant. However, these antibodies act in tissues and induce inflammation and are energy-consuming. In contrast, the milk secretory IgA antibodies stop microbes already on the mucosa preventing infection, tissue engagement and energy loss. In addition, the milk contains many protective factors such as lactoferrin and oligosacharides functioning as analogues for microbial receptors preventing mucosal attachment, the initial step of most infections. As a result, breast-feeding significantly reduces the risk of neonatal septicemia, respiratory tract infections, otitis media, diarrhea, urinary tract infections, infection-induced wheezing and necrotizing enterocolitis. Via several mechanisms it seems that human milk can actively stimulate the immune system of the breast-fed infant. This reduces the risk of infections like otitis media, respiratory tract infections, diarrhea and infection-induced wheezing for several years after the termination of breast-feeding. Furthermore, it seems that breast-feeding decreases the risk of attracting celiac disease and allergic diseases. The latter has been much debated, but a recent critical review of published reports gives good support for long-term protection of allergic diseases, especially in high-risk children.

Nitric oxide induced cervical ripening in the human: Involvement of cyclic guanosine monophosphate, prostaglandin F(2 alpha), and prostaglandin E(2)

OBJECTIVE

The purpose of the study was to investigate possible mechanisms and morphologic changes involved in nitric oxide-induced cervical ripening.

STUDY DESIGN

Women scheduled for surgical termination of first trimester pregnancy were randomized to 1 of 3 groups: isosorbide 5-mononitrate 40 mg 4 hours or 10 hours before the operation or no preoperative treatment. Cervical specimens were obtained for the analysis of tissue levels of cyclic guanosine monophosphate, cyclic adenosine monophosphate, cyclo-oxygenase 1, cyclo-oxygenase 2, prostaglandin F(2 alpha), and prostaglandin E(2) or were fixed in glutaraldehyde for microscopy.

RESULTS

Increased levels of cyclic guanosine monophosphate, cyclo-oxygenase 2, prostaglandin F(2 alpha), and prostaglandin E(2) were found in samples that were exposed to isosorbide 5-mononitrate compared with control samples. Electron microscopy revealed stromal edema and collagen disorganization after isosorbide 5-mononitrate treatment.

CONCLUSION

Cyclic guanosine monophosphate, prostaglandin F(2 alpha), and prostaglandin E(2) are involved in nitric oxide-induced cervical ripening. Nitric oxide causes morphologic changes similar to those changes seen during spontaneous cervical ripening.

The mammary gland-infant intestine immunologic dyad

The human infant has a very small immune system and needs the support of the mother with the transplacentally arrived IgG antibodies to protect tissues with inflammatogenic and energy-consuming defense. The mucous membranes, where most infections occur, need support via the specialized secretory IgA antibodies and the many other mucosal defense mechanisms provided via the mother's milk. This defense is not inflammatogenic and energy-consuming. We learn about additional defense factors in the milk, like the anti-secretory factor, which seems to protect against diarrhoea. The milk contains numerous growth factors and cytokines, like leptin, which may promote the development of the intestine as well as the immune system. Results are appearing giving interesting evidence for enhanced protection against infection also after the termination of breastfeeding. This may occur via the priming of the infant's immune system after uptake of anti-idiotypic antibodies and lymphocytes from the milk. A breastfeeding motivation study in a large Pakistani village resulted in a 50% decrease of diarrhoea and infant mortality. Deep interviews with the mothers and the traditional birth attendants suggested that even better results may be obtained.

Bacterial endotoxin sensitizes the immature brain to hypoxic--ischaemic injury

Epidemiological studies show a markedly increased risk of cerebral palsy following the combined exposure of infection and birth asphyxia. However, the underlying mechanisms of this increased vulnerability remain unclear. We have examined the effects of a low dose of bacterial endotoxin on hypoxic--ischaemic injury in the immature brain of rats. Bacterial endotoxin (lipopolysaccharide 0.3 mg/kg) was administered to 7-day-old rats 4 h prior to unilateral hypoxia--ischaemia and the neurological outcome was determined 3 days later. Rectal temperature and cerebral blood flow was measured during the study and the expression of CD14 and toll-like receptor-4 mRNA in the brain was examined. We found that a low dose of endotoxin dramatically sensitizes the immature brain to injury and induces cerebral infarction in response to short periods of hypoxia--ischaemia that by themselves caused no or little injury. This effect could not be explained by a reduction in cerebral blood flow or hyperthermia. In association with the sensitization of injury we found an altered expression of CD14 mRNA and toll-like receptor-4 mRNA in the brain. These results suggest that the innate immune system may be involved in the vulnerability of the immature brain following the combination of infection and hypoxia--ischaemia.

Orally administered bovine lactoferrin systemically inhibits VEGF(165)-mediated angiogenesis in the rat

Lactoferrin (Lf) systemically suppresses tumor growth and metastasis by unknown mechanisms. We have studied the effect of orally administered iron-unsaturated bovine Lf on angiogenesis induced by VEGF(165) and IL-1-alpha in adult rats using the mesenteric-window angiogenesis assay. VEGF(165) is a major angiogenic factor in most, if not all, tumors and other angiogenesis diseases of clinical relevance. A number of objective angiogenesis variables were analyzed using microscopic morphometry and image analysis. Lf treatment significantly inhibited the VEGF(165)-mediated response in terms of microvessel spatial extension, overall vascularity and incidence of crossover. The response to IL-1-alpha decreased significantly only in terms of microvessel crossover. In vitro, Lf exerted an antiproliferative effect on endothelial cells. To our knowledge, Lf is the first endogenous protein that has been shown to be antiangiogenic following oral administration. The oral administration of Lf thus appears to be of potential interest as an antiangiogenesis treatment modality in the clinical setting. Since tumor growth is angiogenesis dependent, the extensive therapeutic potential warrants further study to elucidate the mechanisms responsible for the angiostatic effect of Lf.

Human lactoferrin and peptides derived from a surface-exposed helical region reduce experimental Escherichia coli urinary tract infection in mice

Lactoferrin (LF) is a multifunctional immunoregulatory protein that has been associated with host defense at mucosal surfaces through its antibacterial properties. The antibacterial and anti-inflammatory properties of LF were further explored with an animal model of experimental urinary tract infection. Bovine LF (bLF), human LF (hLF), and synthetic peptide sequences based on the antibacterial region of hLF (amino acid residues 16 to 40 [HLD1] and 18 to 40 [HLD2]) were given orally to female mice 30 min after the instillation of 10(8) Escherichia coli bacteria into the urinary bladder. The control groups received phosphate-buffered saline or water. C3H/Tif mice were treated with hLF or bLF, and C3H/HeN mice were treated with bLF only. The numbers of bacteria in the kidneys and bladder of C3H/Tif and C3H/HeN mice were significantly reduced 24 h later by the LF treatments compared to the findings for the control group. The hLF-treated group showed the strongest reduction compared with the vehicle-treated-group (P values were 0.009 and 0.0001 for the kidneys and bladder, respectively). The urinary leukocyte response was diminished in the hLF-treated group. The hLF treatment also significantly reduced the urinary interleukin-6 (IL-6) levels at 2 h and the systemic IL-6 levels at 24 h after infection (P values were 0.04 and < 0.002, respectively). In the bLF-treated animals, no such strong anti-inflammatory effects were obtained. In another series of experiments, C3H/Tif mice perorally treated with HLD1 or HLD2 also showed reduced numbers of bacteria in the kidneys compared with the vehicle-treated mice, although the results were significantly different only for HLD2 (P < 0.01). Analysis of urine from hLF-fed C3H/Tif mice showed that hLF was excreted into the urinary tract at 2 h after feeding. Testing of the in vitro bactericidal activity of LF (1 mg/ml) or the peptides (0.1 mg/ml) in mouse urine against the E. coli bacteria revealed moderate killing only by HLD2. In conclusion, these results demonstrate for the first time that oral administration of hLF or peptides thereof is effective in reducing infection and inflammation at a remote site, the urinary tract, possibly through transfer of hLF or its peptides to the site of infection via renal secretion. The antibacterial mechanism is suggested to involve bactericidal capacities of LF, fragments thereof, or its peptides.

[Increased procalcitonin level in bacteriogenic metabolic disturbances. A new possibility for diagnosis and treatment monitoring in sepsis]

Earlier observations of increased plasma concentrations of immunoreactive calcitonin (32 amino acids) in sepsis and other non-tumorous conditions may be explained by increased secretion of procalcitonin, the 116-amino acid prohormone. At present, the site(s) of origin of procalcitonin in sepsis, the factors regulating its biosynthesis and release, the route(s) of its elimination from blood as well as its biological function(s) are unknown. The rapid increase in procalcitonin concentration in sepsis--in some patients earlier than that of C-reactive protein--and decrease upon successful chemotherapy makes procalcitonin a potentially important biomarker in monitoring patients with suspected or confirmed sepsis.

Gastro-intestinal complement activation during human liver transplantation: impact on postoperative liver function

BACKGROUND

Liver transplantation elicits a systemic inflammatory response and eventually a multiple organ failure syndrome. Gastro-intestinal inflammatory activation with release of proinflammatory cytokines and complement activation may occur. This study evaluates gastro-intestinal complement activation and the association with postoperative parenchymatous liver cell injury and liver dysfunction.

METHODS

In 17 patients undergoing liver transplantation, blood samples were collected from radial artery and portal vein for analysis of complement SC5b-9 and endotoxin concentration. Portal venous-arterial SC5b-9 plasma concentration gradients at 30 min after reperfusion were calculated. Outcome parameters included postoperative organ failure and serum concentrations of aspartate aminotransferase, alanine aminotransferase, bilirubin and factor II-VII-X.

RESULTS

Patients with gastro-intestinal SC5b-9 release (n=7) had higher postoperative serum aspartate aminotransferase and alanine aminotransferase concentrations [49 (32-80) microkat/l vs 8 (6-14) microkat/l, P<0.01 and 33 (15-54) microkat/l vs 8 (4-23) microkat/l, P<0.04, respectively] and lower factor II-VII-X concentrations [46 (21-48)% vs 60 (47-69)%, P<0.02] compared to patients without gastro-intestinal SC5b-9 release (n=10). The ICU stay was prolonged in patients with gastro-intestinal complement release. There was no difference in number of organ failures and serum bilirubin concentration between the groups. The endotoxin concentration in arterial and portal vein blood was low and the association between endotoxaemia and complement activation was poor.

CONCLUSION

Gastro-intestinal complement activation may contribute to postoperative parenchymatous liver cell injury and liver dysfunction in patients undergoing liver transplantation.

IL-1beta, IL-6, TNFalpha, fetal fibronectin, and endotoxin in the lower genital tract of pregnant women with bacterial vaginosis

BACKGROUND

In our studies on women with bacterial vaginosis (BV) in early pregnancy a strong association has been found between BV and the levels of endotoxin or interleukin-1alpha (IL-1alpha) in the lower genital tract. In the present study we investigated if an association could be found between BV and other cytokines (IL-1beta, IL-6, tumor necrosis factor alpha, TNF) or fetal fibronectin (FFN). The cytokine-inducing capacity of endotoxins present in the cervical mucus was explored in a monocytic cell assay.

METHODS

Cervical mucus or cervicovaginal fluid was collected from women with (BV) and without BV (nonBV) attending a family planning unit for first trimester abortion. The concentrations of IL-1beta, IL-6, TNF and FFN were determined by quantitative enzyme immunoassays. TNF was determined in 63 women (BV, n=25) out of whom 37 (BV, n=11) were analyzed for IL-1beta and the remaining 26 for IL-6 (BV, n=14). FFN was determined in another 36 women (BV, n= 19). The cytokine-inducing capacity of endotoxin-containing cervical mucus and purified endotoxin of Prevotella bivia were studied by an in vitro cell assay using a human monocytic cell line (THP-1).

RESULTS

IL-lbeta and IL-6 were found in almost all women. The levels of IL-1beta, but not IL-6, TNF or FFN, were significantly increased in women with BV compared with the nonBV women (p<0.05). Purified endotoxin from P. bivia, and cervical mucus from BV women containing high levels of endotoxin were able to induce a cytokine response (IL-6) in monocytic cells in vitro.

CONCLUSION

BV is associated with increased levels of IL-1beta in the lower genital tract of pregnant women in the first trimester. The ability of BV-associated endotoxins to induce cytokine production in monocytic cells may partly explain the increased IL-1beta levels.

Interleukin-1alpha, interleukin-6 and interleukin-8 in cervico/vaginal secretion for screening of preterm birth in twin gestation

BACKGROUND

The purpose was to determine the prognostic value of interleukin (IL) 1-alpha, IL-6 and IL-8 in cervico/vaginal secretion for preterm birth (<37 weeks of gestation) in twin pregnancies.

METHODS

The study included screening of 121 women with twin pregnancies with sampling at 24, 26, 28, 30, 32 and 34 weeks of gestation. IL-1alpha, IL-6 and IL-8 was analyzed with ELISA immunoassays. The detection limit was 30 pg/mL for IL-1 and IL-8 and 40 pg/mL for IL-6. Vaginal fluid was smeared and dried for later evaluation of bacterial vaginosis (presence of clue cells).

RESULTS

Spontaneous preterm birth occurred in 36 women and 65 women were delivered at term. IL-8 was significantly higher (p=0.03) in samples from women delivered preterm (median 3.72 ng/g mucus, range <0.07-220.00) compared with samples from women delivered at term (median 3.03 ng/g mucus, range <0.08-378.60). At 28 weeks of gestation, IL-8 (cut off 1.75 ng/g mucus) was associated with preterm delivery (relative risk 2.2, CI 95% 1.1-4.5) with a sensitivity, specificity, positive and negative predictive value of 78.8, 45.8, 44.8 and 79.4%, respectively. The levels of IL-1alpha and IL-6 were not significantly associated with preterm birth. Bacterial vaginosis was found in 47/541 (8.7%) samples analyzed. The levels of IL-1alpha and IL-8 were significantly higher in samples positive for bacterial vaginosis than in negative samples (p<0.0001 and p<0.01, respectively). There was no significant association between the level of IL-6 and bacterial vaginosis.

CONCLUSIONS

IL-8, but not IL-1alpha and IL-6, was associated with preterm delivery but the relationship was too weak to be of predictive value for preterm birth in twin pregnancies. IL-1alpha and IL-8, but not IL-6, were associated with bacterial vaginosis.

Fetal fibronectin, endotoxin, bacterial vaginosis and cervical length as predictors of preterm birth and neonatal morbidity in twin pregnancies

OBJECTIVE

To evaluate the predictive values of fetal fibronectin, bacterial vaginosis, endotoxin and cervical length for preterm birth (< 35 and < 37 weeks) and neonatal morbidity in twin pregnancies.

PARTICIPANTS

One-hundred and twenty-one women with twin pregnancies recruited into a prospective longitudinal study at three antenatal clinics in the southwest of Sweden.

METHODS

Cervical or vaginal fluid was sampled and determined for fetal fibronectin (> or = 0.05 microgram/mL was used as cutoff), endotoxin (> or = 100 pg/mL) and bacterial vaginosis (presence of clue cells) at two week intervals from 24 to 34 weeks of gestation. The cervical length was measured with transvaginal sonography at the same time intervals.

MAIN OUTCOME MEASURES

Occurrence of preterm birth (< 35 and < 37 weeks of gestation) and neonatal morbidity.

RESULTS

All positive fetal fibronectin samples obtained at screening between 24 and 34 weeks predicted birth < 35 weeks (RR 18.0; 95% CI 2.2-145.9). A positive fetal fibronectin at 28 weeks of gestation predicted delivery < 35 weeks (RR 6.3; 95% CI 2.6-15.1) with a sensitivity, specificity, positive and negative predictive value of 50.0, 92.0, 62.5 and 87.3%, respectively. An independent association between fetal fibronectin at 28 weeks and preterm birth (< 35 weeks) was verified with logistic regression (P = 0.03). A positive fetal fibronectin at 28 weeks of gestation predicted neonatal morbidity (RR 5.1; 95% CI 2.4-11.0) and a longer period of care at the neonatal intensive care unit. The predictive power of cervical sonography was generally low but cervical length (cutoff < or = 33 mm) measured at 28 weeks of gestation was significantly associated with birth < 37 weeks (RR 2.2; 95% CI 1.1-4.2). The presence of endotoxin correlated to bacterial vaginosis, but these tests were not significantly related to preterm birth or neonatal morbidity.

CONCLUSIONS

Fetal fibronectin predicted preterm birth and neonatal morbidity in twin pregnancies. The predictive value of cervical length determinations was low. Endotoxin and bacterial vaginosis had no predictive power for preterm delivery in this study.

Antibodies to Escherichia coli and Shigella flexneri in milk from undernourished mothers: studies on sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated antigens

Analysis of IgA, IgM, and IgG antibodies against Escherichia coli O6, its lipopolysaccharide (LPS), and Shigella flexneri were performed in the milk of moderately undernourished Guatemalan women receiving either a low or a high calorie supplement, using SDS-PAGE. As expected, the immunostaining analysis of milk antibodies showed that IgA was the predominant isotype in both groups. Concerning the other Igs, antibodies against O6 LPS were mainly of the IgM isotype, whereas IgG antibodies were more prominent than IgM against the bacterial whole cell preparations. Seven to nine distinct bands, ranging in molecular mass from 13.5 to 109 kD were selected for each antigen to compare the milk antibodies between the two groups of women. After a 20-wk supplementation period, the IgA and IgG antibodies to the E. coli, O6 LPS, and S. flexneri were not found negatively affected by a low calorie intake. A significantly lower immunostaining intensity was, however, obtained for the low calorie intake group regarding the IgM antibody activity against four high molecular mass bands of the E. coli whole cell preparation. A decreased immunostaining intensity was also found in the same group for IgM antibodies against two bands of E. coli O6 LPS when analyzing paired samples collected at d 0 and wk 20. No differences were found for IgM antibodies against any of the S. flexneri antigens. In conclusion, the results suggest that low calorie intake does not significantly affect the production of milk IgA antibodies to E. coli and S. flexneri antigens in these women. Still, IgM antibodies against certain proteins and LPS molecules of E. coli may be decreased. IgG antibodies, although also present in milk, seemed to be directed mainly against bacterial proteins and not to LPS.

The role of the Lps gene in experimental ulcerative colitis in mice

The effects of the Lps gene on the development of experimental ulcerative colitis were studied in two genetically different mouse strains: C57B1 and C3H. Acute colitis was induced by adding 3% dextran sulfate sodium (DSS) to the drinking water for a 7-day (C57B1 and C3H) or a 10-day (C57B1) experimental period. Although the DSS treatment initiated the same type of morphological changes in the colon in all groups of mice, an earlier onset and persistent intestinal bleeding occurred in the Lpsn mice (sensitive to lipopolysaccharide, LPS) in comparison with the Lpsd mice (hyporesponsive to LPS). Rectal bleeding appeared on day 7 in 90% of the Lpsn compared to 13% of the Lpsd mice (p < 0.0001). In C57B1 mice, followed for three additional days, 50% of the Lpsn mice died and the surviving animals showed as well as rectal bleeding a large number of Gram-negative bacteria in the liver and spleen. In contrast, the Lpsd mice of the C57B1 strain appeared unaffected by the treatment, although a transient rectal bleeding occurred in 90% on day 8. Also, significantly fewer Gram-negative bacteria were found in the liver and spleen. Even though significantly increased serum endotoxin levels were seen in all DSS-treated groups compared to controls on day 7, the serum levels of TNF alpha were significantly increased only in the Lpsn mice. In DSS-induced colitis the Lpsn genotype conferred on the mice an increased LPS susceptibility, resulting in an augmentation of the inflammatory response to Gram-negative bacteria and their endotoxins. The results suggest that LPS-induced host effector mechanisms significantly enhanced the intestinal bleeding, systemic inflammatory response, and mortality in mice with DSS-induced colitis. In addition, the host defense against the invading and systemically spread bacteria most probably involved additional genes.