Annelie Brauner

The antimicrobial peptide cathelicidin protects the urinary tract against invasive bacterial infection

The urinary tract functions in close proximity to the outside environment, yet must remain free of microbial colonization to avoid disease. The mechanisms for establishing an antimicrobial barrier in this area are not completely understood. Here, we describe the production and function of the cathelicidin antimicrobial peptides LL-37, its precursor hCAP-18 and its ortholog CRAMP in epithelial cells of human and mouse urinary tract, respectively. Bacterial contact with epithelial cells resulted in rapid production and secretion of the respective peptides, and in humans LL-37/hCAP-18 was released into urine. Epithelium-derived cathelicidin substantially contributed to the protection of the urinary tract against infection, as shown using CRAMP-deficient and neutrophil-depleted mice. In addition, clinical E. coli strains that were more resistant to LL-37 caused more severe urinary tract infections than did susceptible strains. Thus, cathelicidin seems to be a key factor in mucosal immunity of the urinary tract.

Uropathogenic Escherichia coli Modulates Immune Responses and Its Curli Fimbriae Interact with the Antimicrobial Peptide LL-37

Bacterial growth in multicellular communities, or biofilms, offers many potential advantages over single-cell growth, including resistance to antimicrobial factors. Here we describe the interaction between the biofilm-promoting components curli fimbriae and cellulose of uropathogenic E. coli and the endogenous antimicrobial defense in the urinary tract. We also demonstrate the impact of this interplay on the pathogenesis of urinary tract infections. Our results suggest that curli and cellulose exhibit differential and complementary functions. Both of these biofilm components were expressed by a high proportion of clinical E. coli isolates. Curli promoted adherence to epithelial cells and resistance against the human antimicrobial peptide LL-37, but also increased the induction of the proinflammatory cytokine IL-8. Cellulose production, on the other hand, reduced immune induction and hence delayed bacterial elimination from the kidneys. Interestingly, LL-37 inhibited curli formation by preventing the polymerization of the major curli subunit, CsgA. Thus, even relatively low concentrations of LL-37 inhibited curli-mediated biofilm formation in vitro. Taken together, our data demonstrate that biofilm components are involved in the pathogenesis of urinary tract infections by E. coli and can be a target of local immune defense mechanisms.

Early increase of TNFα and IL-6 in tracheobronchial aspirate fluid indicator of subsequent chronic lung disease in preterm infants

AIM To investigate if early changes in concentrations of proinflammatory cytokines in tracheobronchial aspirate fluid (TAF) from preterm infants could be used to detect infants at risk of chronic lung disease (CLD) and help in the selection of patients for early steroid treatment. METHODS Twenty eight preterm infants less than 34 weeks of gestation (median 26 weeks) were intubated and daily measurements of TAF concentrations of tumour necrosis factor α (TNFα) and the interleukins IL-1β, IL-6, and IL-8 were made, using enzyme immunoassay techniques. RESULTS Seventeen of the infants developed CLD. The infants who developed CLD had significantly increased concentrations of TNFα, IL-1ß, IL-6 on days 2 and 3. TNFα, IL-6, and IL-8 concentrations were significantly related to gestational age and duration of supplemental oxygen; TNFα, IL-6, and IL-8 concentrations also correlated with length of time on the ventilator. CONCLUSION These data indicate that tracheobronchial aspirate fluid cytokine concentrations may be used as a predictor of subsequent CLD and may help select a group of preterm infants at high risk of developing CLD for early treatment.

Non-infected preterm parturition is related to increased concentrations of IL-6, IL-8 and MCP-1 in human cervix.

BackgroundHuman cervical ripening is an inflammatory process. In labour at term the mRNA-levels and protein concentrations for interleukin-6 (IL-6) and IL-8 in cervix significantly increase. The aim of this study was to investigate if there are differences in the inflammatory process of preterm and term cervical ripening.MethodsCervical biopsies from 50 singleton pregnant women without clinical signs of infection were allocated to four groups: preterm labour, term labour, preterm not in labour and term not in labour. The protein levels of IL-8, IL-6, monocyte chemotactic protein-1 (MCP-1), regulated upon activation normal t cells expressed and secreted (RANTES) and tumour necrosis factor-alpha (TNF-alpha) were quantified in tissue homogenates by ELISA or Immulite. The mRNA expression of IL-8, MCP-1 and RANTES was studied using RT-PCR. White blood cell count (WBC) and C-reactive protein (CRP) in the blood were determined. For determination of statistically significant differences between study groups Mann-Whitney U test or Kruskal-Wallis test were applied.ResultsProtein concentrations of IL-8, IL-6, and MCP-1 were significantly increased during labour compared to non-labouring groups, whereas no changes were observed for RANTES and TNF-alpha. The mRNA levels of representative cytokines such as IL-8 and MCP-1 increased significantly during labour whereas RANTES mRNA expression remained unchanged. WBC and CRP were significantly higher in the labouring groups as compared to groups not in labour. For neither of the analysed cytokines, WBC or CRP levels were there any changes between preterm and term respective groups.ConclusionOur findings indicate that non-infected preterm cervical ripening is an inflammatory process, just as cervical ripening at term, with cytokines as important mediators.

Interleukin-8 is a mediator of the final cervical ripening in humans

OBJECTIVE The aim of the present study was to investigate the presence of interleukin-8 (IL-8) in the human cervix and whether the levels of interleukin-8 could be related to the ripening process during pregnancy. STUDY DESIGN Cervical biopsies were obtained in twelve term pregnant and in eight vaginally delivered women. Seven non-pregnant fertile women served as controls. After homogenisation and centrifugation, IL-8 levels were determined in the supernatant by an enzyme-immunoassay (EIA). RESULTS In women at term, the concentration of IL-8 increased six-fold from median 330 pg/ml to median 2190 pg/ml (P < 0.001). After the final cervical ripening it increased in additional 11-fold to median 26,100 pg/ml (P < 0.001). These changes are highly significant. CONCLUSION To our knowledge, this is the first time IL-8 has been identified in human cervix. Our results support the involvement of IL-8 in the connective tissue remodelling during the final cervical ripening just before onset of labour.

Vitamin D Induction of the Human Antimicrobial Peptide Cathelicidin in the Urinary Bladder

The urinary tract is frequently being exposed to potential pathogens and rapid defence mechanisms are therefore needed. Cathelicidin, a human antimicrobial peptide is expressed and secreted by bladder epithelial cells and protects the urinary tract from infection. Here we show that vitamin D can induce cathelicidin in the urinary bladder. We analyzed bladder tissue from postmenopausal women for expression of cathelicidin, before and after a three-month period of supplementation with 25-hydroxyvitamin D3 (25D3). Cell culture experiments were performed to elucidate the mechanisms for cathelicidin induction. We observed that, vitamin D per se did not up-regulate cathelicidin in serum or in bladder tissue of the women in this study. However, when the bladder biopsies were infected with uropathogenic E. coli (UPEC), a significant increase in cathelicidin expression was observed after 25D3 supplementation. This observation was confirmed in human bladder cell lines, even though here, cathelicidin induction occurred irrespectively of infection. Vitamin D treated bladder cells exerted an increased antibacterial effect against UPEC and colocalization to cathelicidin indicated the relevance of this peptide. In the light of the rapidly growing problem of resistance to common urinary tract antibiotics, we suggest that vitamin D may be a potential complement in the prevention of UTI.

Soluble interleukin-1 receptor type II levels are elevated in cerebrospinal fluid in Alzheimer's disease patients.

Evidence from epidemiological, clinical and experimental studies favour the hypothesis that inflammatory events are part of the neuropathology in Alzheimers disease. Proinflammatory cytokines such as interleukin-1 (IL-1), interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-alpha) have been found in activated microglia in the vicinity of amyloid plaques in Alzheimers disease brain. In the present study, the levels of soluble IL-1 receptor type II (sIL-1R type II), IL-1 receptor antagonist (IL-1ra), IL-1beta, IL-6 and TNF-alpha were analyzed in cerebrospinal fluid (CSF) samples from Alzheimers disease patients and control subjects. The levels of sIL-1R type II were significantly higher in CSF from Alzheimers disease patients than in CSF samples from control subjects (38.5+/-8 pg/ml (mean+/-S.E.M.) vs. 7.9+/-4 pg/ml, p<0.05). Measurements of the proinflammatory cytokines IL-6 and TNF-alpha showed no significant difference between the two groups, and the levels of IL-1beta and IL-1ra in the present material were too low to permit detection. The increased levels of sIL-1R type II may reflect a compensatory mechanism to balance an increased release of IL-1 receptor agonists in the Alzheimers disease brain.

Interleukin-6 and interleukin-8 in serum and urine in patients with acute pyelonephritis in relation to bacterial-virulence-associated traits and renal function

Urine and serum concentrations of interleukin (IL)-6 and IL-8 were determined in 43 women with acute pyelonephritis caused by Escherichia coli. Urine and serum samples were also collected 2 weeks after the infection and during a subsequent episode of cystitis (n = 8) or asymptomatic bacteriuria (n = 8). Concentrations of IL-6 and IL-8 were related to the expression of 5 virulence markers of E. coli and glomerular filtration rate (GFR) after pyelonephritis. Patients with acute pyelonephritis had elevated urine and serum IL-6 and IL-8 levels as compared to 37 healthy women (IL-6: p < 0.001 in both cases, and IL-8: p < 0.001 in both cases). Patients infected with E. coli producing hemolysin and/or cytotoxic necrotizing factor (CNF) had significantly higher IL-6 levels in serum during acute pyelonephritis as compared to patients infected with strains without the ability to produce these factors (p = 0.0025 and p = 0.0154, respectively). Patients who had high concentrations of IL-8 in urine during acute pyelonephritis had lower GFR at follow-up as compared to patients with lower levels of IL-8 in urine (r = -0.48, p = 0.0123). In conclusion, acute pyelonephritis is accompanied by elevated urinary and serum IL-6 and IL-8 levels. Bacteria producing hemolysin and CNF seem to induce higher concentrations of IL-6 in serum. The secretion of IL-8 from renal cells may participate in the initiation and maintenance of renal inflammation which in turn may influence renal function.

Tumor necrosis factor-α, interleukin-1β, and interleukin-1 receptor antagonist in dialysate and serum from patients on continuous ambulatory peritoneal dialysis

Abstract Dialysate and serum levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-1ra were investigated in 20 patients on continuous ambulatory peritoneal dialysis (CAPD), who altogether had 30 episodes of peritonitis. Bacterial growth was found in 25 (83%) of the dialysate samples. Staphylococcus epidermidis was the single most common microorganism, found in 44% of the culture-verified peritonitis. Samples from dialysate bags were obtained during the first month of dialysis and during peritonitis from the first three bags on day 1 (the day of admittance) and from nightbags on days 3 and 10. Serum samples were drawn on days 1 and 10. The peak concentrations of cytokines occurred on the first day of infection. In dialysates, TNF-α was elevated in 96% of the patients, with a peak median concentration of 160 pg/mL (range, P P P

Ureaplasma urealyticum -Induced Production of Proinflammatory Cytokines by Macrophages

Ureaplasma urealyticum is relatively common in the respiratory tract of very low birth weight infants and has been hypothesized to be involved in the development of chronic lung disease. The purpose of this study was to investigate whether U. urealyticum could stimulate macrophages to produce proinflammatory cytokines in vitro, which are early pathologic changes in the lung during the development of chronic lung disease. A human monocytic cell line (THP-1) differentiated to macrophages, a rat alveolar macrophage cell line (Nr8383), and human lung macrophages from tracheobronchial aspirate fluid in preterm infants were exposed to U. urealyticum antigen for 24 h. The protein levels of human IL-6, tumor necrosis factor-α (TNF-α), and rat TNF-α were measured with ELISA. Rat IL-6 was analyzed with a specific bioassay. The mRNA levels of these cytokines were detected by reverse transcriptase-PCR. The production of TNF-α and IL-6 increased after stimulation with U. urealyticum in both the human and rat macrophage cell lines. In tracheobronchial aspirate fluid macrophages, U. urealyticum increased the production of TNF-α from 14 to 84% and IL-6 from 46 to 268% above control levels. U. urealyticum also induced gene expression of TNF-α and IL-6. In conclusion, U. urealyticum could be an important factor in the development of chronic lung disease because of its ability to induce alveolar macrophage proinflammatory cytokine production.