Inger Mattsby-Baltzer

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.

Lactoferrin or a Fragment Thereof Inhibits the Endotoxin-Induced Interleukin-6 Response in Human Monocytic Cells

Human milk is in several ways anti-inflammatory. This study investigates whether or not human milk lactoferrin (LF) in comparison with bovine LF can affect the IL-6 release from human cells. Human, as well as bovine, LF and a bactericidal pepsin-derived fragment of bovine LF (lactoferricin B) were found to suppress the IL-6 response in a monocytic cell line (THP-1) when stimulated by lipopolysaccharide (LPS). The suppression of bovine LF was similar to or higher than that of human LF. Lactoferricin B was the strongest inhibitor of the LPS-induced IL-6 response. A time-dependence regarding the inhibitory capacity of LF was found. For human LF, the strongest inhibition was observed when added 15-30 min after the addition of LPS. Addition of LF before the LPS induced an approximately 45% reduction of the IL-6 response. The results suggest an anti-inflammatory activity of both human and bovine LF, and of the LF fragment lactoferricin B through their suppressive effects on the cytokine release.

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.

The Transfer of Immunity from Mother to Child

Abstract: The newborns 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.

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.

Human Lactoferrin and Peptides Derived from a Surface-Exposed Helical Region Reduce Experimental Escherichia coli Urinary Tract Infection in Mice

ABSTRACT 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 108Escherichia 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.

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.

Bacterial vaginosis - a microbiological and immunological enigma

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.

IL‐1β, IL‐6, TNFα, 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.

Endotoxin and interleukin-1α in the cervical mucus and vaginal fluid of pregnant women with bacterial vaginosis*

OBJECTIVE The purpose of our study was to determine the concentrations of endotoxin and interleukin-1 alpha in the cervical mucus and vaginal fluid of pregnant women who either did or did not have bacterial vaginosis. STUDY DESIGN Samples of cervical mucus and vaginal fluid were collected from women in early pregnancy who had signs of bacterial vaginosis and from healthy control subjects. The samples were analyzed for the concentrations of endotoxin and interleukin-1 alpha. In addition, wet mounts were examined for signs of inflammation indicated by increased numbers of leukocytes. RESULTS Both endotoxin and interleukin-1 alpha occurred in much higher concentrations (p < 0.0001, p < 0.0002) in both the cervical mucus and the vaginal fluid of women with signs of bacterial vaginosis than they did in healthy control subjects. A correlation was found between the interleukin-1 alpha concentrations in the vaginal fluid and the number of leukocytes as judged by a semi-quantitative evaluation of wet mounts (p = 0.0365). The concentrations of endotoxin correlated with those of interleukin-1 alpha in both fluids (vaginal fluid, p < 0.01; cervical mucus, p < 0.01). CONCLUSION Our study shows that concentrations of endotoxin and interleukin-1 alpha in cervical mucus and vaginal fluid of women in early pregnancy who have bacterial vaginosis are significantly higher than the corresponding levels in control subjects.