Microbial/host interactions in health and disease: who controls the cytokine network?

Molecular investigation of Coxiella burnetii in the Middle and East Black Sea region in aborted bovine fetuses and investigation of the oxidant/antioxidant system

Coxiella burnetii (C. burnetii) is a causative microorganism that causes the zoonotic Q fever disease, which is generally asymptomatic in animals, but causes reproductive issues such as abortion, stillbirth, and infertility. C. burnetii infection poses a threat to farm economies as it affects productivity in farm animals. The purpose of this research was to look into the incidence of Q fever in eight provinces in the Middle and East Black Sea region and to measure reactive oxygen and reactive nitrogen species as well as antioxidant levels in bovine aborted fetal livers infected with C. burnetii. The study material consisted 670 bovine aborted fetal liver samples delivered to Samsun Veterinary Control Institute from eight provinces between 2018 and 2021. C. burnetii was analyzed by PCR in these samples and 47 (7,01%) were positive while 623 negative. Nitric oxide (NO), malondialdehyde (MDA) and reduced glutathione (GSH) activities were analyzed by spectrophotometric method in both 47 positive samples and 40 negative samples as control group. In the C. burnetii positive and control groups, MDA levels were determined to be 2.46 ± 0.18 and 0.87 ± 0.07 nmol/ml, NO levels were determined to be 1.77 ± 0.12 and 1.09 ± 0.07 nmol/ml, and reduced GSH activity was determined to be 5.14 ± 0.33 and 6.62 ± 0.46 µg/dl, respectively. In C. burnetii positive fetal liver tissue, MDA and NO levels were higher than the control group, while reduced GSH levels were lower than the control group. As a result, C. burnetii caused changes in free radical level and antioxidant activity in bovine aborted fetus liver.

Exacerbation of allergic rhinitis by the commensal bacterium Streptococcus salivarius

Allergic rhinitis (AR)-commonly called hay fever-is a widespread condition that affects the quality of life of millions of people. The pathophysiology of AR remains incompletely understood. In particular, it is unclear whether members of the colonizing nasal microbiota contribute to AR. Here, using 16S ribosomal RNA sequencing, we show that the nasal microbiome of patients with AR (n = 55) shows distinct differences compared with that from healthy individuals (n = 105), including decreased heterogeneity and the increased abundance of one species, Streptococcus salivarius. Using ex vivo and in vivo models of AR, we demonstrate that this commensal bacterium contributes to AR development, promoting inflammatory cytokine release and morphological changes in the nasal epithelium that are characteristic of AR. Our data indicate that this is due to the ability of S. salivarius to adhere to the nasal epithelium under AR conditions. Our study indicates the potential of targeted antibacterial approaches for AR therapy.

Salmonella as a Promising Curative Tool against Cancer

Bacteria-mediated cancer therapy has become a topic of interest under the broad umbrella of oncotherapy. Among many bacterial species, Salmonella remains at the forefront due to its ability to localize and proliferate inside tumor microenvironments and often suppress tumor growth. Salmonella Typhimurium is one of the most promising mediators, with engineering plasticity and cancer specificity. It can be used to deliver toxins that induce cell death in cancer cells specifically, and also as a cancer-specific instrument for immunotherapy by delivering tumor antigens and exposing the tumor environment to the host immune system. Salmonella can be used to deliver prodrug converting enzymes unambiguously against cancer. Though positive responses in Salmonella-mediated cancer treatments are still at a preliminary level, they have paved the way for developing combinatorial therapy with conventional chemotherapy, radiotherapy, and surgery, and can be used synergistically to combat multi-drug resistant and higher-stage cancers. With this background, Salmonella-mediated cancer therapy was approved for clinical trials by U.S. Food and Drug Administration, but the results were not satisfactory and more pre-clinical investigation is needed. This review summarizes the recent advancements in Salmonella-mediated oncotherapy in the fight against cancer. The present article emphasizes the demand for Salmonella mutants with high stringency toward cancer and with amenable elements of safety by virulence deletions.

The effect of zirconia and titanium surfaces on biofilm formation and on host-derived immunological parameters

The aim of this study was to analyse the effect of zirconia and titanium surfaces on biofilm formation and host-derived parameters. Studies comparing zirconia and titanium surfaces were selected up to September 1, 2019. The outcome measures were surface roughness, contact angle, bacterial count, bacterial adherence, biofilm thickness, bacterial distribution, and specifically investigated biofilm and specific host-derived immunological parameters. Random-effects meta-analyses of in vitro and in vivo studies were conducted. A total of 39 studies were included for data extraction. In the systematic review data, 10 studies stated that zirconia accumulated less initial oral biofilm parameters, 16 investigations showed negligible inter-material differences, and only one study showed that zirconia attracted the most biofilm. However, in the meta-analysis, the bacterial coverage was found to be significantly superior for zirconia surfaces (P< 0.00001); the other outcome measures did not show any statistically significant differences between zirconia and titanium for the remaining parameters and the studies presented a substantial degree of heterogeneity. Overall, on the basis of the meta-analysis, the current data situation does not allow a clear preference for the use of zirconia or titanium.

Acute phase proteins, proinflammatory cytokines and oxidative stress biomarkers in sheep, goats and she-camels with Coxiella burnetii infection-induced abortion

Acute phase proteins (APPs) and oxidative stress are helpful markers in diagnosis of several infectious diseases. APPs, proinflammatory cytokines and oxidative stress markers were evaluated for their role in the diagnosis of naturally acquired Coxiella burnetii (Q fever) associated with abortion in sheep, goats and she-camels. Blood, aborted materials and vaginal swabs were collected from mixed herds in the Eastern Province of Saudi Arabia. Antioxidant biomarkers showed significant decline in cases of abortion compared to control animals at delivery time. The correlation between disease status and all parameters ranged from moderate to high. The APPs, cytokines and the oxidative stress marker malondialdehyde (MDA) displayed a high degree of distinction between aborted sheep and goat and normal delivered animals (AUC > 0.90). However, only MDA showed a high degree of differentiation (AUC > 0.90) between aborted she-camels and normal delivered controls. In conclusion, results from our study allow us to recommend using APPs, cytokines and oxidative stress markers as an additional tool for diagnosis of naturally occurring C. burnetii infection in sheep, goats and she-camels. However, it does not replace standard procedures for detection of C. burnetii.

Strains, Mechanism, and Perspective: Salmonella-Based Cancer Therapy

Recently, investigation of bacterial-based tumor therapy has regained focus due to progress in molecular, cellular, and microbial biology. Many bacteria such as Salmonella, Listeria, Escherichia, and Clostridium have proved to have tumor targeting and in some cases even tumor-destroying phenotypes. Furthermore, bacterial clinical treatments for cancer have been improved by combination with other therapeutic methods such as chemotherapeutic drugs and radioactive agents. Synthetic biology techniques have also driven the development of new bacterial-based cancer therapies. However, basic questions about the mechanisms of bacterial-mediated tumor targeting and destruction are still being elucidated. In this review, we focus on three tumor-therapeutic Salmonella models, the most intensively studied bacterial genus in this field. One of these Salmonella models is our Salmonella enterica serovar Typhimurium LT2 derived strain CRC2631, engineered to minimize toxicity but maximize tumor-targeting and destruction effects. The other two are VNP20009 and A1-R. We compare the means by which these therapeutic candidate strain models were selected for study, their tumor targeting and tumor destruction phenotypes in vitro and in vivo, and what is currently known about the mechanisms by which they target and destroy tumors.

Mechanisms of fever production and lysis: lessons from experimental LPS fever

Fever is a cardinal symptom of infectious or inflammatory insults, but it can also arise from noninfectious causes. The fever-inducing agent that has been used most frequently in experimental studies designed to characterize the physiological, immunological and neuroendocrine processes and to identify the neuronal circuits that underlie the manifestation of the febrile response is lipopolysaccharide (LPS). Our knowledge of the mechanisms of fever production and lysis is largely based on this model. Fever is usually initiated in the periphery of the challenged host by the immediate activation of the innate immune system by LPS, specifically of the complement (C) cascade and Toll-like receptors. The first results in the immediate generation of the C component C5a and the subsequent rapid production of prostaglandin E2 (PGE2). The second, occurring after some delay, induces the further production of PGE2 by induction of its synthesizing enzymes and transcription and translation of proinflammatory cytokines. The Kupffer cells (Kc) of the liver seem to be essential for these initial processes. The subsequent transfer of the pyrogenic message from the periphery to the brain is achieved by neuronal and humoral mechanisms. These pathways subserve the genesis of early (neuronal signals) and late (humoral signals) phases of the characteristically biphasic febrile response to LPS. During the course of fever, counterinflammatory factors, "endogenous antipyretics," are elaborated peripherally and centrally to limit fever in strength and duration. The multiple interacting pro- and antipyretic signals and their mechanistic effects that underlie endotoxic fever are the subjects of this review.

Probiotic Bio-Three induces Th1 and anti-inflammatory effects in PBMC and dendritic cells

AIM: To investigate the immune response of peripheral blood mononuclear cells (PBMCs) and dendritic cells (DCs) that were stimulated by probiotic preparations.

METHODS: PBMCs were isolated, cultured, and stimulated with Bio-Three (a mixture of Bacillus mesentericus, Clostridium butyricum and Enterococcus faecalis; 10⁵, 10⁶ and 10⁷ CFU/mL for 24 h). Cytokine production of (1) circulating PBMCs; (2) PBMCs stimulated by probiotic preparation; (3) monocyte-derived DCs; and (4) DC and T cell co-culture was determined by enzyme-linked immunosorbent assay. Phenotypic analysis of circulating PBMCs was also investigated by flow cytometry. Blood was obtained from individuals who consumed Bio-Three (10⁹ CFU/d B. mesentericus, C. butyricum and E. faecalis) for 2 wk, or those who did not take probiotics orally.

RESULTS: In culture supernatants, interferon-γ (IFN-γ) and interleukin (IL)-10 production increased, but IL-4 and tumor necrosis factor-α (TNF-α) production by PBMCs decreased after 1 and 2 wk of probiotic treatment. Flow cytometry was also performed on day 14 and detected enhanced expression of CD11b, HLA-DR, CD4, CD45RA, CD25, CD44 and CD69 in response to Bio-Three. Furthermore, IL-10 and IL-12 were upregulated in supernatants of monocyte-derived DCs, and IFN-γ and IL-10 were enhanced in supernatants of CD4⁺ T cells co-cultured with DCs.

CONCLUSION: Bio-Three appeared to stimulate the Th1 immune response, downregulate pro-inflammatory cytokines (TNF-α) and upregulate anti-inflammatory cytokine (IL-10). Probiotics could be effective in activation of PBMCs and DCs.

The bacterial signal indole increases epithelial-cell tight-junction resistance and attenuates indicators of inflammation

Interkingdom signaling is established in the gastrointestinal tract in that human hormones trigger responses in bacteria; here, we show that the corollary is true, that a specific bacterial signal, indole, is recognized as a beneficial signal in intestinal epithelial cells. Our prior work has shown that indole, secreted by commensal Escherichia coli and detected in human feces, reduces pathogenic E. coli chemotaxis, motility, and attachment to epithelial cells. However, the effect of indole on intestinal epithelial cells is not known. Because intestinal epithelial cells are likely to be exposed continuously to indole, we hypothesized that indole may be beneficial for these cells, and investigated changes in gene expression with the human enterocyte cell line HCT-8 upon exposure to indole. Exposure to physiologically relevant amounts of indole increased expression of genes involved in strengthening the mucosal barrier and mucin production, which were consistent with an increase in the transepithelial resistance of HCT-8 cells. Indole also decreased TNF-alpha-mediated activation of NF-kappaB, expression of the proinflammatory chemokine IL-8, and the attachment of pathogenic E. coli to HCT-8 cells, as well as increased expression of the antiinflammatory cytokine IL-10. The changes in transepithelial resistance and NF-kappaB activation were specific to indole: other indole-like molecules did not elicit a similar response. Our results are similar to those observed with probiotic strains and suggest that indole could be important in the intestinal epithelial cells response to gastrointestinal tract pathogens.

Role for tumor necrosis factor alpha (TNF-alpha) and interleukin 1-beta (IL-1beta) determination in seminal plasma during infertility investigation

OBJECTIVE

To evaluate the clinical relevance of tumor necrosis factor alpha (TNF-alpha) and interleukin 1-beta (IL-1beta) determination in seminal plasma during infertility investigation.

DESIGN

Prospective study.

SETTING

Outpatient infertility clinic of a university-based hospital.

PATIENT(S)

Randomly chosen asymptomatic males (n = 148) from subfertile couples.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Determination of TNF-alpha and IL-1beta in seminal plasma (SP) by enzyme-linked immunosorbent assay (ELISA). In aliquots of the same ejaculates: 1) evaluation of semen quality with sperm analysis and sperm function testing; 2) determination of antisperm antibodies (ASA) of the immunoglobulin (Ig) G and IgA class; 3) microbial screening; and 4) immunocytochemical round cell differentiation to determine leukocyte counts and ratios. Medical history, clinical examination, and determination of subsequent fertility (after control for female infertility factors).

RESULT(S)

The concentrations of TNF-alpha and IL-1beta in SP correlated significantly (r = 0.65; P<.0001), and these parameters were significantly related to the leukocyte ratio (%LC) of the seminal round cells (r = 0.36; P<.001) and the leukocyte counts per ejaculate (r = 0.34; P<.001). There was no relationship of TNF-alpha and IL-1beta levels in SP with semen quality or parameters of sperm functional capacity, and there was no association with local ASA of the IgG or IgA class. The concentration of both cytokines was also not related to the outcome of the microbial screening and did not affect subsequent fertility. No correlation of TNF-alpha and IL-1beta levels in SP with the concentration of C-reactive protein in same-day serum samples was found.

CONCLUSION(S)

The levels of TNF-alpha and IL-1beta in seminal fluid correlate significantly with leukocyte counts and ratios in the same ejaculates, as indicators of silent male genital tract infection/inflammation. However, this is not related to semen cultures in asymptomatic individuals and not associated with clinically relevant parameters of semen quality, including sperm fertilizing capacity.

An update on Behçet's disease

Behçet's disease (Adamantiades-Behçet's disease, ABD) is a multisystemic inflammatory disease, the pathogenesis of which is still a mystery. Many questions are still to be answered and the available diverse data need to be brought together to be compared and analysed. There is at least consensus on the effect of possible, but currently unknown, environmental triggering factor(s) against a background of genetic susceptibility. The possible aetiological factors form a broad spectrum, with infectious agents being the most probable ones. Whatever the stimulus is, the target tissue seems to be the small blood vessels, with various consequences of either vasculitis and/or thrombosis in many organ systems. The endothelium seems to be the primary target in this disease; however, it may just be the subject of the bizarre behaviour of the immune system. The diverse existing data could be interpreted in favour of either explanation. A similar confusion exists about the thrombotic tendency in Adamantiades-Behçet's disease, in terms of whether a primary hypercoagulability is present or whether it is secondary to inflammation. Recent interesting immunological data promise a way out of the existing dilemma. These findings will be outlined within the context of possible hypotheses and attention will be paid to further investigations that are needed.

Effect of sulfur dioxide inhalation on cytokine levels in lungs and serum of mice

In order to elucidate the immunotoxic mechanism exerted by sulfur dioxide (SO(2)), we investigated the effect of SO(2), a major air pollutant, on the cytokine levels in lungs and serum of male mice. Levels of interlukin-6(IL-6), tumor necrosis factor-alpha (TNF-alpha), and transforming growth factor-beta1 (TGF-beta1) in lungs and serum from male mice exposed to SO(2) at various concentrations were measured by the enzyme-linked immunosorbent assay. Sixty Kunming albino male mice were divided randomly into six equal groups: three groups exposed to SO(2) (14.00 +/- 1.25, 28.00 +/- 1.98, and 56.00 +/- 3.11 mg/m(3), which are 5 +/- 0.45, 10 +/- 0.71, and 20 +/- 1.11 ppm) and their respective control groups. The results were as follows: (1) For lung tissues of male mice, exposure to SO(2) at 14 mg/m(3) (5 ppm) caused statistically significant increase of levels of IL-6 and TNF-alpha (p < .05) compared with the control group; exposure at 28 mg/m(3) (10 ppm) caused a statistically highly significant increase of level of IL-6 (p < .01) and a significant increase of TNF-alpha (p < .05); and exposure at 56 mg/m(3) (20 ppm) caused no any significant increase of levels of IL-6 and TNF-alpha. SO(2) at all concentrations tested could not cause significant change of level of TGF-beta1 in lungs. (2) For serum from male mice, after exposure to SO(2) at 14 mg/m(3) (5 ppm), the level of TNF-a was significantly increased (p < .05) compared with the control group, but the changes of levels of IL-6 and TGF-beta1 were not significant. After exposure to SO(2) at 28 mg/m(3) (10 ppm) and 56 mg/m(3) (20 ppm), levels of IL-6 and TNF-alpha were increased nonsignificantly, but the level of TGF-beta1 was decreased nonsignificantly. These results imply that inflammation reaction could be induced in lung tissue by SO(2) inhalation and the inflammation reaction might relate to these cytokines. And determination of cytokines in lung may be more valuable than in serum when lung injury caused by SO(2).

Consequences of semen inflammation and lipid peroxidation on fertilization capacity of spermatozoa in in vitro conditions

A body of data exists on reactive oxygen species (ROS) release, however, no direct correlation was found between the oxidative stress and infertility. The aim of the study was to measure semen oxidative stress and its correlation with classical in vitro fertilization (IVF) rate. A prospective study in academic non-profit institution where 79 infertile couples were subjected to IVF programme was conducted. Two infertile groups were discriminated according to the pronuclei presence in IVF. The main outcome measure (pronuclei presence) was then correlated with lipid peroxidation product in semen (ROS effect). Although the average IL-8 levels and malondialdehyde (MDA) content in semen did not differ between the studied subgroups (successful vs. non-successful fertilization), a statistically significant negative correlation was found between MDA level and fertilization rate in performed regression analysis. Thus we may suggest that MDA levels in seminal plasma may have prognostic value for IVF success.

Macrolide antibiotics in food-animal health

Several 14- and 16-membered-ring macrolide antibiotics have acquired important roles in the modern production of food animals. Macrolide antibiotics exhibit many similar antimicrobial properties whether used in veterinary or human medicine. In addition to their direct inhibitory action on micro-organisms, macrolides exert a variety of subinhibitory concentration (sub-MIC) effects that are being increasingly recognised as important factors in the explanation of therapeutic results. Macrolides achieve wide tissue distribution and high intracellular concentrations that contribute prominently to their efficacy. Another important factor governing efficacy is the complex interaction between macrolides, micro-organisms, and phagocytes that may enable the host defence system to enhance the antibiotic's inhibitory action. A potential role for macrolides in modulating inflammatory processes has also been recognised. In both sub-MIC effects and interactions with the host immune system, different macrolides exert different responses that may reinforce or oppose each other. This complexity of responses requires additional studies in appropriate disease states and animal species in order to elucidate a more comprehensive understanding and explanation of in vivo outcomes.

Anti-human immunodeficiency virus type 1 microbicide cellulose acetate 1,2-benzenedicarboxylate in a human in vitro model of vaginal inflammation

The sexual transmission of human immunodeficiency virus type 1 (HIV-1) is facilitated by inflammation and related epithelial barrier perturbation. Microbicides for vaginal applications are currently being developed to reduce the risk of HIV-1 transmission. However, little is known about their interference with epithelial immune function. In recent clinical trials, nonoxynol-9 (N-9), a virucide with a long history of intravaginal use as a contraceptive, failed to protect against HIV-1 possibly due to mucosal inflammatory damage. Cellulose acetate 1,2-benzenedicarboxylate, also named CAP (for "controls AIDS pandemic"), is an anti-HIV-1 microbicide selected from pharmaceutical excipients that are regarded as safe for oral administration but have not been assessed for potential effects on inflammatory factors in the vaginal environment. Here we use a sensitive human cell culture system to evaluate proinflammatory profiles of soluble CAP in reference to N-9 and known epithelial activators such as tumor necrosis factor alpha (TNF-alpha) and bacterial lysates. Within 6 h of exposure, TNF-alpha and N-9 triggered NF-kappaB and AP-1/cFos activation and upregulated interleukins and an array of chemokines by vaginal and polarized cervical epithelial cells. The induced proinflammatory status continued after removal of stimuli and was confirmed by enhanced transepithelial neutrophil migration. While sustaining stability and anti-HIV-1 activity in the epithelial environment, CAP did not increase the production of proinflammatory mediators during or after exposure, nor did it modify the epithelial resistance to leukocyte traffic. CAP attenuated some TNF-alpha-induced responses but did not interfere with epithelial cytokine responsiveness to gonococcal determinants. The described system may be useful for predicting proinflammatory side effects of other microbicide candidates for vaginal application.

Apoptotic effects of LPS on fibroblasts are indirectly mediated through TNFR1

During periods of periodontal attachment loss, one of the most significant cellular changes is a decrease in the number of fibroblasts. We previously demonstrated that LPS induces apoptosis of fibroblastic cells in vivo, largely through TNF-alpha. We conducted in vivo experiments by subcutaneous inoculation of LPS in wild-type, TNFR1-/-R2-/-, TNFR1-/-, and TNFR2-/- mice to identify which TNF receptors are involved and the specific caspase pathway activated. LPS stimulated apoptosis through TNFR1 but not TNFR2, which was accompanied by the induced expression of 12 apoptotic genes. Fluorometric studies demonstrated that LPS in vivo significantly increased caspase-8 and caspase-3 activity, which was also dependent on TNF receptor signaling. By the use of specific caspase inhibitors, caspases-3 and -8 were shown to play an important role in LPS-induced apoptosis in vivo. Thus, LPS acts through TNFR1 to modulate the expression of apoptotic genes and activate caspases-3 and -8.

Lipopolysaccharides Indirectly Stimulate Apoptosis and Global Induction of Apoptotic Genes in Fibroblasts

Following Gram-negative bacterial infection there is a reduction in matrix-producing cells. The goal of the present study was to examine the apoptotic effects of lipopolysaccharide (LPS) on fibroblastic cells and to investigate the role that the host response plays in this reaction. This was accomplished in vivo by subcutaneous inoculation of LPS in wild type and TNFR1(-/-)R2(-/-) mice. The direct effects of LPS on fibroblast apoptosis was studied in vitro with normal diploid human fibroblasts. The results indicate that LPS in vivo induces apoptosis of fibroblasts. By RNA profiling we demonstrated that LPS stimulates global expression of apoptotic genes and down-regulates anti-apoptotic genes. Fluorometric studies demonstrated that LPS in vivo significantly increased caspase-8 and caspase-3 activity and by use of specific inhibitors, the activation of caspase-3 was shown to be initiated by caspase-8 with no contribution from caspase-9. In vitro studies demonstrated that LPS did not induce apoptosis of fibroblasts, whereas tumor necrosis factor (TNF) did. In addition, the pattern of apoptotic gene expression induced by TNF in vitro was nearly identical to that induced by LPS in vivo, as measured by RNase protection assay. Moreover, pre-treatment of cells with TNF greatly enhanced apoptosis induced by a second stimulation with TNF 24 h later, suggesting that the global induction of pro-apoptotic genes was functionally significant. Thus, LPS acts to modulate the expression of a large number of genes that favor apoptosis of fibroblastic cells that is dependent upon activation of caspase-8 and is largely mediated by TNF.

Innate immunity and pathogen-host interaction

The skin and contiguous mucosal surfaces define the primary locus of interaction between host and micro-organisms. In this review, we focus on the innate immune system in the mucosa, which manages to deal with invading pathogens, the mechanisms that organisms have evolved in order to circumvent this primary defensive barrier and, finally, potential therapeutic manipulation of the innate immune system that was the focus of meeting at a Euroconference/Workshop on "Novel Strategies of Mucosal Immunisation through Exploitation of Mechanisms of Innate Immunity in Pathogen-Host Interaction", which was held in Siena, Italy, November 2002.

Effects of various applications of lipopolysaccharides on blood parameters of pigs

In five experiments, lipopolysaccharides (LPS) of Escherichia coli O26:B6 and O111:B4 were applied intravenously, intramuscularly, subcutaneously or intrabronchially in doses of 5000-15,000 U/kg body mass to a total of 47 weaner pigs and compared with the application of sodium chloride. Different parameters of blood cells were investigated, including cell numbers, in vivo interleukin secretion, radical formation, phagocytosis capacity and IL-6 as well as TNFalpha formation ex vivo. Non-specific effects and dependencies on the type of application and LPS dose are discussed.

Early enteral supply of lactobacillus and fiber versus selective bowel decontamination: a controlled trial in liver transplant recipients

BACKGROUND

Early enteral nutrition with solutions containing prebiotics (fiber) and probiotics (Lactobacillus) is suggested to reduce bacterial translocation and minimize the incidence of infections after liver transplantation.

METHODS

In a prospective, randomized placebo-controlled trial consisting of 95 patients, we compared the incidence of postoperative infections and other complications after liver transplantation among three different groups, all supplied with early enteral nutrition: (a) standard formula plus selective bowel decontamination (SBD), (b) fiber-containing formula plus living Lactobacillus plantarum 299, and (c) fiber-containing formula plus heat-killed L plantarum 299.

RESULTS

The groups were comparable regarding preoperative American Society of Anesthesiologists classification, Child-Pugh classification of cirrhosis, operative data, and degree of immunosuppression. The patients who received living lactobacilli plus fiber developed significantly fewer bacterial infections (13%) than the patients with SBD (48%). The incidence of infections was 34% in the group with inactivated lactobacilli and fiber. Cholangitis and pneumonia were the leading infections and enterococci the most commonly isolated bacteria. In the living Lactobacillus group, the mean duration of antibiotic therapy, the mean total hospital stay, and the stay on the intensive care unit were also shorter than in the groups with inactivated lactobacilli and fiber as well as with SBD. However, these differences did not reach statistical significance.

CONCLUSIONS

Early enteral nutrition with fiber-containing solutions and living L plantarum 299 was well tolerated. It decreases markedly the rate of postoperative infections both in comparison with inactivated L plantarum 299 and significantly with SBD and a standard enteral nutrition formula. As it is a cheap and feasible alternative to SBD, further studies should evaluate whether this ecoimmunonutrition should be already started while patients are on the waiting list for transplantation.

Endovascular approach to abdominal aortic aneurysms limits the postoperative systemic immune response

OBJECTIVES

endovascular repair of abdominal aortic aneurysms (E-AAA) has in recent years developed as an alternative to the conventional open repair (C-AAA). Adverse outcomes following the open approach may relate to immune cell activation and the systemic inflammatory response syndrome (SIRS) and organ failure but the benefits in this respect of the endovascular approach are unclear. This study evaluated this question and focused on T-cell activation and function.

DESIGN

prospective clinical study.

MATERIALS

twenty patients undergoing abdominal aortic aneurysm repair (12 C-AAA and 8 E-AAA).

METHODS

peripheral T-cell expression of surface markers CD69, CD62L and CD25 in vivo and Interleukin 2 (IL-2) and Interleukin-10 (IL-10) responses to the superantigen staphylococcal enterotoxin B (SEB) in vitro were measured preoperatively, 24 h and 1 week postoperatively.

RESULTS

there was no significant increase (p=0.23) in the incidence of SIRS in the open compared with the endovascular group. Enhanced T cell activation occurred following C-AAA and this was associated with significantly greater IL-2 production in response to SEB, with no change in IL-10 production.

CONCLUSIONS

E-AAA attenuates proinflammatory T-cell changes compared with C-AAA repair. A reduction in T-cell activation and impaired responsiveness to superantigen suggests that the immunological sequelae of the endovascular approach to aneurysm repair is more favourable than after the open approach with potentially less risk of adverse outcomes. Proof of this thesis will require a larger prospective study.

Seminal antibodies to human 60kd heat shock protein (HSP 60) in male partners of subfertile couples

BACKGROUND

Heat shock proteins (HSP) are essential mammalian and bacterial stress proteins. At the cellular level, they act as chaperones, have important regulatory functions, and are considered to be an essential factor for reproduction. Scarce information exists on the role of sensitization to HSP and the potential role in the aetiology of male infertility.

METHODS

The potential association of immunoglobulin (Ig)A antibodies (Ab) to the human 60 kDa heat shock protein (HSP 60) with several parameters of subclinical male genital tract infection/inflammation and with semen quality and sperm fertilizing capacity was analysed in a prospective study. IgA Ab to human HSP 60 were determined in seminal plasma of 202 randomly chosen male partners of subfertile couples with a median duration of infertility of 4 years (range 1-15 years), who were asymptomatic for genital tract infection. After medical history and clinical examination, a comprehensive evaluation of semen quality, in aliquots of the same ejaculates used for HSP Ab determination, included: sperm analysis; local antisperm antibody (ASA) screening; standardized sperm-cervical mucus (CM) penetration testing; immunocytochemical round cell differentiation to determine seminal leukocyte counts; evaluation of complement fraction C(3) and of some pro-inflammatory cytokines; and microbial screening. Subsequent fertility was recorded after 6 months.

RESULTS

The presence of HSP 60 IgA Ab in seminal fluid (total positive 6.9%) was significantly associated with leukocytospermia, the presence of C(3), and also with high interleukin (IL) levels in seminal plasma. HSP 60 Ab were not related to the bacterial colonization of ejaculates. There was no association of seminal IgA Ab to human HSP 60 with semen quality, determined with microscopical semen analysis, nor with local IgG- or IgA-class ASA. There was no relationship with sperm intrinsic motility and duration of motility in the sperm CM-penetration test, nor with sperm fertilizing capacity.

CONCLUSIONS

The combined presence of IgA Ab to human 60 kDa HSP, leukocytes and other established infection/inflammation markers in semen might suggest a potential role of the immune response to heat shock proteins (HSP) in cases of silent male genital tract infection, but the results do not indicate a marked relationship of HSP 60 Ab in seminal fluid with standard parameters of semen quality.

Concurrent inflammation as a determinant of susceptibility to toxicity from xenobiotic agents

Sensitivity to the toxic effects of xenobiotic agents is influenced by a number of factors. Recent evidence derived from studies using experimental animals suggests that inflammation is one of these factors. For example, induction of inflammation by coexposure to bacterial endotoxin, vitamin A or Corynebacterium parvum increases injury in response to a number of xenobiotic agents that target liver. These agents are diverse in chemical nature and in mechanism of hepatotoxic action. Factors critical to the augmentation of liver injury by inflammation include Kupffer cells, neutrophils, cytokines such as tumor necrosis factor-alpha (TNF-alpha) and lipid mediators such as prostaglandins, but these may vary depending on the xenobiotic agent and the mechanisms by which it alters hepatocellular homeostasis. In addition, the timing of inflammagen exposure can qualitatively alter the toxic response to chemicals. Inflammation-induced increases in susceptibility to toxicity are not limited to liver. Concurrent inflammation also sensitizes animals to the toxic effects of agents that damage the respiratory tract, kidney and lymphoid tissue. It is concluded that inflammation should be considered as a determinant of susceptibility to intoxication by xenobiotic exposure.

Preliminary evidence for Herpes labialis recurrence following experimentally induced disgust

BACKGROUND

After primary orofacial infection with the herpes simplex virus (type 1, HSV-1), up to 40% of HSV seropositive subjects suffer recurrent herpes infections which are characterized by painful erosions of the involved skin mainly around the lips (herpes labialis). Besides various other factors, there is growing evidence suggesting that psychosocial factors might trigger HSV. The present study was designed to investigate modulation of recurrent HSV infection by experimentally induced emotional distress.

METHODS

Among patients with herpes labialis (n = 91), subjects who showed recurrent HSV infection (>5 acute infections/year) and who reported to suffer from HSV symptoms exclusively after confrontation with dirty dishes, i.e. dirty plates or dirty glasses were selected by standardized interview. Subjects (n = 20) were randomly assigned to two treatment groups. The experimental group (n = 10) was first exposed to 5 slides showing dirty glasses and subsequently to the glasses previously presented on the slides in vivo. The control group (n = 10) was exposed to neutral slides and neutral objects. In order to determine the proportion of leukocyte subpopulations and concentrations of tumor necrosis factor alpha (TNF-alpha), blood samples were collected 15 min before as well as 40 min and 48 h after stimulus presentation. Saliva cortisol was obtained 45, 20, 15 and 1 min before and 1, 10, 20 and 30 min after stimulus confrontation.

RESULTS

Medical examination of the volunteers 48 h after the experiment indicated that four experimental subjects showed HSV-1 symptoms while not a single herpetic infection could be determined in the control subjects (p = 0.033). Moreover, significantly elevated concentrations of TNF-alpha were observed in the experimental, but not in the control group. No significant alterations of the number of leukocyte subpopulations were found 30 min or 48 h after stimulus presentation. Further, cortisol concentrations were found to be unchanged after the treatment.

CONCLUSIONS

The present findings suggest that experimentally induced emotional stress such as disgust may be associated with reactivation of HSV.

Relationship of seminal plasma interleukin (IL) -8 and IL-6 with semen quality

The concentration of interleukin (IL) -8 and IL-6 was determined in seminal plasma (SP) samples from 137 randomly chosen subfertile males to evaluate the relationship with other potential parameters of subclinical infection/inflammation such as seminal leukocytes, and with semen quality in a prospective study. All patients were asymptomatic for genital tract infection. A comprehensive semen evaluation included sperm analysis, sperm migration testing, antisperm antibody screening, immunocytochemical round cell differentiation to determine seminal leukocytes counts and the leukocyte ratio, complement fraction C(3) (C(3c)) determination, and semen cultures, in aliquots of the same ejaculates. The SP concentration of IL-8 was inversely related to semen quality, e.g. to the total number of motile spermatozoa or to the outcome of the sperm migration test (motile sperm harvested after a swim-up procedure). IL-8 concentrations were significantly correlated with leukocyte counts per ml (P < 0.0001) and per ejaculate (P < 0.0001), and with the leukocyte ratio (P < 0.001). All leukocytospermic samples had high IL-8 concentrations (< or =2 ng/ml). The SP concentration of IL-6 was much lower, but was significantly correlated with IL-8 (P < 0.0001). Both IL-8 and IL-6 were significantly related with the C(3c). No association of interleukin concentrations with the bacterial colonization of semen samples was found. The results indicate a marked relationship of some pro-inflammatory cytokines with semen quality. The significant association with seminal leukocytes and other potential inflammation markers suggests that IL-8 might be used as sensitive marker for silent male genital tract infection.

Cells and cytokines in inflammatory secretions of bovine mammary gland

In response to invading bacteria, the mammary gland is protected by a variety of defence mechanisms, which can be separated into two distinct categories: innate immunity and specific immunity. Milk somatic cells consist of several cell types, including neutrophils, macrophages, lymphocytes and a smaller percentage of epithelial cells. In the healthy lactating mammary gland, macrophages are the predominant cell type whereas neutrophils are the major cell population during early inflammation. Following a bacteria invasion, neutrophil recruitment is elicited by inflammatory mediators that are produced in the infected gland by cells, possibly macrophages, activated by bacteria phagocytosis or responding to bacterial toxins or metabolites. Several cytokines, including interleukin- (IL-) 1 beta, IL-6, IL-8, tumour necrosis factor- (TNF-) alpha and interferon- (IFN-) gamma are known to be important to elicit the acute phase response and allow the accumulation of leukocytes at the site of infection. In addition to their role in early non-specific defences, macrophages also play a key role in the specific immune system, as antigen processing and presenting cells for the T cells. Few lymphocytes are found in milk of healthy glands where the predominant phenotype is CD8+ T cells. During the inflammatory reaction, T cells are recruited in milk and CD4+ cells become the predominant phenotype. The understanding of the specific and nonspecific immune mechanisms involved in the mammary gland defence against invading bacteria may lead to the development of new vaccines and to the use of cytokines to design immunomodulatory strategies for the control of bovine mastitis.

Modulation of cytokine release in ex vivo-stimulated blood from borreliosis patients

In lipopolysaccharide-stimulated blood from 71 late-stage borreliosis patients, the ex vivo cytokine release capacity of tumor necrosis factor alpha (TNF-alpha) and gamma interferon (IFN-gamma) was reduced to 28% +/- 5% and to 31% +/- 5% (P < or = 0.001), respectively, compared to that of 24 healthy controls. White blood cell counts were normal in both groups. To investigate direct interactions between the pathogen and the immune cells, blood from healthy controls was exposed in vitro to live or heat-killed Borrelia or to Borrelia lysate. Compared to the pattern induced by bacterial endotoxins, a reduced release of TNF-alpha and IFN-gamma and an enhanced secretion of interleukin-10 and granulocyte colony-stimulating factor was found. In blood from 10 borreliosis patients stimulated with Borrelia lysate, TNF-alpha formation was decreased to 31% +/- 14% and IFN-gamma formation was decreased to 8% +/- 3% (P < or = 0.001) compared to the cytokine response of blood from healthy controls (n = 24). We propose to consider anti-inflammatory changes in the blood cytokine response capacity elicited by Borrelia as a condition that might favor the persistence of the spirochete.

Probiotics: effects on immunity

The gastrointestinal tract functions as a barrier against antigens from microorganisms and food. The generation of immunophysiologic regulation in the gut depends on the establishment of indigenous microflora. This has led to the introduction of novel therapeutic interventions based on the consumption of cultures of beneficial live microorganisms that act as probiotics. Among the possible mechanisms of probiotic therapy is promotion of a nonimmunologic gut defense barrier, which includes the normalization of increased intestinal permeability and altered gut microecology. Another possible mechanism of probiotic therapy is improvement of the intestine's immunologic barrier, particularly through intestinal immunoglobulin A responses and alleviation of intestinal inflammatory responses, which produce a gut-stabilizing effect. Many probiotic effects are mediated through immune regulation, particularly through balance control of proinflammatory and anti-inflammatory cytokines. These data show that probiotics can be used as innovative tools to alleviate intestinal inflammation, normalize gut mucosal dysfunction, and down-regulate hypersensitivity reactions. More recent data show that differences exist in the immunomodulatory effects of candidate probiotic bacteria. Moreover, distinct regulatory effects have been detected in healthy subjects and in patients with inflammatory diseases. These results suggest that specific immunomodulatory properties of probiotic bacteria should be characterized when developing clinical applications for extended target populations.

Cloning and expression of the Actinobacillus actinomycetemcomitans thioredoxin (trx) gene and assessment of cytokine inhibitory activity

Thioredoxin is a ubiquitous redox control and cell stress protein. Unexpectedly, in recent years, thioredoxins have been found to exhibit both cytokine and chemokine activities, and there is increasing evidence that this class of protein plays a role in the pathogenesis of inflammatory diseases. In spite of this evidence, it has been reported that the oral bacterium and periodontopathogen Actinobacillus actinomycetemcomitans secretes an immunosuppressive factor (termed suppressive factor 1 [SF1] [T. Kurita-Ochiai and K. Ochiai, Infect. Immun. 64:50-54, 1996]) whose N-terminal sequence, we have determined, identifies it as thioredoxin. We have cloned and expressed the gene encoding the thioredoxin of A. actinomycetemcomitans and have purified the protein to homogeneity. The A. actinomycetemcomitans trx gene has 52 and 76% identities, respectively, to the trx genes of Escherichia coli and Haemophilus influenzae. Enzymatic analysis revealed that the recombinant protein had the expected redox activity. When the recombinant thioredoxin was tested for its capacity to inhibit the production of cytokines by human peripheral blood mononuclear cells, it showed no significant inhibitory capacity. We therefore conclude that the thioredoxin of A. actinomycetemcomitans does not act as an immunosuppressive factor, at least with human leukocytes in cultures, and that the identity of SF1 remains to be elucidated.

Ionizing radiation and bacterial challenge alter splenic cytokine gene expression

Irradiation increases susceptibility to bacterial infection. Exogenous proinflammatory cytokines can alter the response of mice to gamma radiation, but the role of endogenous inflammatory cytokines after bacterial infection in irradiated animals is not known. Gene expression of hematopoietic (GM-CSF) and proinflammatory (IL-1 beta, IL-6 and TNF-alpha) cytokines were examined in spleens of B6D2F1/J female mice after irradiation alone (1.0- and 7.0-Gy), and after irradiation followed by Klebsiella pneumoniae s.c. challenge 4 days postirradiation by using the reverse transcription-polymerase chain reaction (RT-PCR) and Southern blot hybridization. At 4, 8, and 24 h after bacterial challenge in 7.0-Gy-irradiated mice, GM-CSF mRNA increased (p < 0.05). TNF-alpha mRNA in irradiated mice were slightly decreased, whereas after bacterial challenge, TNF-alpha mRNA elevated at 30 h in 7.0-Gy-irradiated mice; at 4, and 8 h in 1.0-Gy-irradiated mice, and at 1 h in sham-irradiated mice (p < 0.05). IL-6 mRNA displayed a biphasic response in 7.0-Gy-irradiated mice, and, after bacterial challenge, in both irradiated mice (1.0- and 7.0-Gy) and sham-irradiated mice. IL-1 beta mRNA remained at or below normal for 8 h and increased at 24 h after bacterial challenge on day 4 in 7.0-Gy-irradiated mice. These results indicate that sublethal gamma radiation alters the patterns of the hematopoietic and proinflammatory cytokine responses to bacterial challenge in vivo. Consequently, treatment protocols may need to take into account changes in cytokine gene responses to resolve infection after irradiation.

Involvement of small GTPases in Mycoplasma fermentans membrane lipoproteins-mediated activation of macrophages

Mycoplasma fermentans lipoproteins (LAMPf) are capable of activating macrophages and inducing the secretion of proinflammatory cytokines. We have recently reported that mitogen-activated protein kinase (MAPK) pathways and NF-kappaB and activated protein 1 (AP-1) play a crucial role in the activation induced by this bacterial compound. To further elucidate the mechanisms by which LAMPf mediate the activation of macrophages, we assessed the effects of inhibiting small G proteins Rac, Cdc42, and Rho. The Rho-specific inhibitor C3 enzyme completely abolished the secretion of tumor necrosis factor alpha by macrophages stimulated with LAMPf and also inhibited the activation of extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal kinase (JNK), and p38 kinase. In addition, we have shown that LAMPf stimulate Cdc42 and that inhibition of Cdc42 or Rac by dominant negative mutants abrogates LAMPf-mediated activation of JNK and transactivation of NF-kappaB and AP-1 in the murine macrophage cell line RAW 264.7. These results indicate that small G proteins Rho, Cdc42, and Rac are involved in the cascade of events leading to the macrophage activation by mycoplasma lipoproteins.

Guideline for Prevention of Surgical Site Infection, 1999. Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee

EXECUTIVE SUMMARY The "Guideline for Prevention of Surgical Site Infection, 1999" presents the Centers for Disease Control and Prevention (CDC)'s recommendations for the prevention of surgical site infections (SSIs), formerly called surgical wound infections. This two-part guideline updates and replaces previous guidelines.1,2 Part I, "Surgical Site Infection: An Overview," describes the epidemiology, definitions, microbiology, pathogenesis, and surveillance of SSIs. Included is a detailed discussion of the pre-, intra-, and postoperative issues relevant to SSI genesis. Part II, "Recommendations for Prevention of Surgical Site Infection," represents the consensus of the Hospital Infection Control Practices Advisory Committee (HICPAC) regarding strategies for the prevention of SSIs.3 Whenever possible, the recommendations in Part II are based on data from well-designed scientific studies. However, there are a limited number of studies that clearly validate risk factors and prevention measures for SSI. By necessity, available studies have often been conducted in narrowly defined patient populations or for specific kinds of operations, making generalization of their findings to all specialties and types of operations potentially problematic. This is especially true regarding the implementation of SSI prevention measures. Finally, some of the infection control practices routinely used by surgical teams cannot be rigorously studied for ethical or logistical reasons (e.g., wearing vs not wearing gloves). Thus, some of the recommendations in Part II are based on a strong theoretical rationale and suggestive evidence in the absence of confirmatory scientific knowledge.It has been estimated that approximately 75% of all operations in the United States will be performed in "ambulatory," "same-day," or "outpatient" operating rooms by the turn of the century.4 In recommending various SSI prevention methods, this document makes no distinction between surgical care delivered in such settings and that provided in conventional inpatient operating rooms. This document is primarily intended for use by surgeons, operating room nurses, postoperative inpatient and clinic nurses, infection control professionals, anesthesiologists, healthcare epidemiologists, and other personnel directly responsible for the prevention of nosocomial infections. This document does not: Specifically address issues unique to burns, trauma, transplant procedures, or transmission of bloodborne pathogens from healthcare worker to patient, nor does it specifically address details of SSI prevention in pediatric surgical practice. It has been recently shown in a multicenter study of pediatric surgical patients that characteristics related to the operations are more important than those related to the physiologic status of the patients.5 In general, all SSI prevention measures effective in adult surgical care are indicated in pediatric surgical care. Specifically address procedures performed outside of the operating room (e.g., endoscopic procedures), nor does it provide guidance for infection prevention for invasive procedures such as cardiac catheterization or interventional radiology. Nonetheless, it is likely that many SSI prevention strategies also could be applied or adapted to reduce infectious complications associated with these procedures. Specifically recommend SSI prevention methods unique to minimally invasive operations (i.e., laparoscopic surgery). Available SSI surveillance data indicate that laparoscopic operations generally have a lower or comparable SSI risk when contrasted to open operations.6-11 SSI prevention measures applicable in open operations (e.g., open cholecystectomy) are indicated for their laparoscopic counterparts (e.g., laparoscopic cholecystectomy). Recommend specific antiseptic agents for patient preoperative skin preparations or for healthcare worker hand/forearm antisepsis. Hospitals should choose from products recommended for these activitie

Guideline for prevention of surgical site infection, 1999. Hospital Infection Control Practices Advisory Committee

The “Guideline for Prevention of Surgical Site Infection, 1999” presents the Centers for Disease Control and Prevention (CDC)'s recommendations for the prevention of surgical site infections (SSIs), formerly called surgical wound infections. This two-part guideline updates and replaces previous guidelines.

Part I, “Surgical Site Infection: An Overview,” describes the epidemiology, definitions, microbiology, pathogenesis, and surveillance of SSIs. Included is a detailed discussion of the pre-, intra-, and postoperative issues relevant to SSI genesis.

Gut microenvironment and immune function

Overreaction of the acute phase response is responsible for the two major complications to surgery, sepsis and thrombosis, but also most likely for the leading sequela to surgery, adhesion formation. The gastrointestinal tract, especially the colon, is a major player in the acute phase response and responsible for important immune functions with important interactions between the commensal flora, mucosal cells and the mucosa/gut associated lymphoid tissues. These responses can effectively be modulated by enteral nutrition, provided it is properly composed and administered. There is increasing evidence that the important clinical effects sometimes observed in enteral nutrition are more related to immunostimulatory effects than to reduction in microbial translocation. It is suggested that in order to be effective enteral nutrition should be instituted if possible before the operation, but always at least immediately after. Furthermore, much supports that the formula given should contain what has been called colonic food, e.g. plant fibres, and have a low content of saturated fat. Use of antibiotics with deleterious effects on the commensal flora should also be limited as much as possible. Lack of compliance with these requests seems to explain the lack of consistency in clinical experience of enteral nutrition, when tried in connection with trauma and clinical surgery.

Intrauterine infusion of bacterial lipopolysaccharide (LPS) prior to mating has no adverse effect on fertility, fetal survival and fetal development

Lipopolysaccharide (LPS, endotoxin) is a component of the cell wall of gram-negative bacteria and a potent inducer of severe inflammatory reactions. In mice, systemically administered LPS induces fetal resorption and increases fetal mortality. However, effects of intrauterine LPS on fertility, fetal survival and development have not been reported. In the present study, pigs were used to determine the effect of intrauterine infused LPS on fertility, fetal survival and development. Prior to mating, gilts received intrauterine infusion of either a single dose of saline or increasing doses of LPS in saline using an insemination catheter. On day 30 of pregnancy, gilts were hysterectomized and litter size, fetal length, number of corpora lutea (CL), ovarian and placental weights, and allantoic and amniotic fluid volumes were recorded. Blood progesterone levels from days 10-30 of pregnancy were also determined. Results indicated that intrauterine infusion of LPS had no adverse effects on blood progesterone levels, fertility, fetal survival or fetal development. Intrauterine injection of LPS did cause an increase in fetal weight and amniotic fluid volume (P < 0.05). These results suggest that sperm, oocytes and gametes are tolerant of local LPS challenge and, to some extent, this mechanism protects gametes and conceptuses from maternal response to mating introduced bacteria and their potential endotoxins.

Commensal communism and the oral cavity

The world we live in contains unimaginable numbers of bacteria, and these and other single-celled creatures represent the major diversity of life on our planet. During the last decade or so, the complexity and intimacy of the interactions which occur between bacteria and host eukaryotic cells during the process of infection have begun to emerge. The study of such interactions is the subject of the new discipline of cellular microbiology. This intimacy of bacteria/host interactions creates a major paradox. The average human being is 90% bacteria in terms of cell numbers. These bacteria constitute the commensal or normal microflora and populate the mucosal surfaces of the oral cavity, gastrointestinal tract, urogenital tract, and the surface of the skin. In bacterial infections, much of the pathology is due to the release of a range of bacterial components (e.g., modulins such as lipopolysaccharide, peptidoglycan, DNA, molecular chaperones), which induce the synthesis of the local hormone-like molecules known as pro-inflammatory cytokines. However, such components must also be constantly released by the vast numbers of bacteria constituting the normal microflora and, as a consequence, our mucosae should constantly be in a state of inflammation. This is patently not the case, and a hypothesis is forwarded to account for this "commensal paradox", namely, that our commensal bacteria and mucosal surfaces exist in a state of bio-communism, forming a unified "tissue" in which interactions between bacteria and epithelia are finely balanced to ensure bacterial survival and prevent the induction of damaging inflammation. Evidence is emerging that bacteria can produce a variety of proteins which can inhibit the synthesis/release of inflammatory cytokines. The authors predict that such proteins are simply one part of an extensive signaling system which occurs between bacteria and epithelial cells at mucosal surfaces such as those found in the oral cavity.

Homogeneous Escherichia coli Chaperonin 60 Induces IL-1β and IL-6 Gene Expression in Human Monocytes by a Mechanism Independent of Protein Conformation

Escherichia coli chaperonin (cpn) 60 (groEL) is a protein-folding oligomer lacking tryptophan residues that copurifies with tryptophan-containing proteins and peptides. Cpn 60 is a major immunogen in infectious diseases, and evidence suggests that groEL and mycobacterial cpn 60s can induce cytokine synthesis, stimulate cytokine-dependent bone resorption, and up-regulate expression of vascular endothelial cell adhesion molecules. Whether such activities are due to the cpn 60 or to the copurifying/contaminating proteins/peptides has not been determined. Here we report a method for removing the protein contaminants of groEL and demonstrate that this, essentially homogeneous, groEL remains a potent inducer of human monocyte IL-1β and IL-6 production. Contaminating peptides had no cytokine-inducing activity and did not synergize with purified groEL. The LPS inhibitor polymyxin B and the CD14-neutralizing Ab MY4 had no inhibitory action on groEL demonstrating that activity is not due to LPS contamination. Heating groEL had no effect on its capacity to stimulate human monocytes to secrete IL-6. Proteolysis of groEL with trypsin, sufficient to produce low molecular mass peptides, also had no inhibitory effect. Thus, we conclude that groEL is a potent inducer of monocyte proinflammatory cytokine production, which acts through the binding of nonconformational peptide domains that are conserved after proteolysis. These data suggest that if groEL was released from bacteria it could induce prolonged tissue pathology by virtue of its cytokine-inducing activity and its resistance to proteolytic inhibition of bioactivity.

Involvement of TNF alpha, IL-1 beta and IL-1 receptor antagonist in LPS-induced rabbit uveitis

The objective of the study was to investigate involvement of TNF alpha, IL-1 beta and IL-1 receptor antagonist (IL-1Ra) in lipopolysaccharide (LPS)-induced uveitis. Intravitreal injection of LPS (100 ng) to rabbits induced a massive leukocyte infiltration and protein leakage into the aqueous humor. Aqueous leukocyte counts and protein levels reached a peak 24 hr after this injection. The peak concentrations of aqueous TNF alpha (230 +/- 37 pg ml-1, at 9 hr) and IL-1 beta (185 +/- 80 pg ml-1, at 18 hr) preceded peak levels of aqueous leukocyte counts and protein levels. In contrast, the levels of aqueous IL-1Ra peaked at 48 hr (12,239 +/- 1964 pg ml-1) and a fairly high concentration of IL-1Ra remained when the inflammatory reactions subsided. Immunohistochemistry and leukocyte-depletion studies showed that infiltrating leukocytes were the major cellular sources of aqueous TNF alpha, IL-1 beta and IL-1Ra. Intravitreal injection of homologous TNF alpha (0.1-1.5 micrograms) or IL-1 beta (0.5-5 ng) reproduced a rapid leukocyte infiltration and protein leakage. Administration of anti-TNF alpha mAb (10 micrograms) suppressed the number of LPS-induced infiltrating neutrophils by 50%, mononuclear cells by 58%, and protein leakage by 42%. Administration of rabbit IL-1Ra (10 micrograms) also suppressed neutrophil influx by 78%, however, neither mononuclear cell influx nor protein leakage was inhibited by rabbit IL-1Ra. Co-administration of the two inhibitors enhanced inhibition of neutrophil infiltration to 88%, and protein leakage to 64%. We conclude that TNF alpha and IL-1 beta are the principal mediators of LPS-induced uveitis. Our observations also suggest that endogenous IL-1Ra may down-regulate inflammatory reactions.

Are bacterial exotoxins cytokine network regulators?

Bacterial exotoxins are generally thought to act by damaging cells or altering cell metabolism. However, recent work has established that many exotoxins modulate eukaryotic cell cytokine synthesis. Cytokine induction may play a significant role in exotoxin action, and therapeutic targeting of cytokines could be beneficial in infectious diseases involving bacterial exotoxins.