Cytokines acting on or secreted by macrophages during intracellular infection (IL-10, IL-12, IFN-gamma)

Lactic acid bacteria enhance autophagic ability of mononuclear phagocytes by increasing Th1 autophagy-promoting cytokine (IFN-gamma) and nitric oxide (NO) levels and reducing Th2 autophagy-restraining cytokines (IL-4 and IL-13) in response to Mycobacterium tuberculosis antigen

BACKGROUND AND OBJECTIVES

Control of the intracellular Mycobacterium tuberculosis (Mtb), mainly requires an appropriate ratio of Th1/Th2 cytokines to induce autophagy, a physiologically, and immunologically regulated process that has recently been highlighted as an innate defense mechanism against intracellular pathogens. Current vaccines/adjuvants induce both protective Th1 autophagy-promoting cytokines, such as IFN-gamma, and immunosuppressive Th2 autophagy-restraining cytokines, such as IL-4 and IL-13. TB infection itself is also characterized by relatively high levels of Th2 cytokines, which down-regulate Th1 responses and subsequently subvert adequate protective immunity, and a low ratio of IFN-gamma/IL-4. Therefore, there is a need for a safe and non-toxic vaccine/adjuvant that will induce Th1 autophagy-promoting cytokine (IFN-gamma) secretion and suppress the pre-existing subversive Th2 autophagy-restraining cytokines (IL-4 and IL-13). As lactic acid bacteria (LAB) belonging to the natural intestinal microflora and their components have been shown to shift immune responses against other antigens from Th2-type cytokines toward Th1-type cytokines like IFN-gamma, we investigated whether LAB can improve the polarization of Th1/Th2 cytokines and autophagic ability of mononuclear phagocytes in response to Mtb antigen.

METHODS

Peripheral blood mononuclear cells (PBMCs), which are a part of the mononuclear phagocyte system and source of crucial macrophage activators in the in vivo situation, and human monocyte-derived macrophages (HMDMs) were treated with Mtb antigen in the presence or absence of two strains of LAB, L. rhammosus GG (LGG) and Bifidobacterium bifidum MF 20/5 (B.b). PBMCs cell culture supernatants were analyzed for the production of the autophagy-promoting factors IFN-gamma, and nitric oxide (NO) and the autophagy-restraining cytokines IL-4 and IL-13, using ELISA and Griess assays to detect the production of cytokines and NO, respectively. In HMDMs, expression of microtubule-associated protein 1 light chain 3 (LC3-I), membrane-associated (LC3-II) forms of LC3 protein and Beclin-1, as hallmarks of autophagy, were assessed using Western blot to detect the autophagy markers. The secreted interleukin 6 (IL-6), interleukin 10 (IL-10), interleukin (IL)-12 and transformig growth factor-beta (TGF-beta), and chemokine (C-C motif) ligand 18 (CCL18) from HMDMs were determined by ELISA. Also, reverse transcription polymerase chain reaction (RT-PCR) analysis was used to assess the mRNA expressions of CCL18 in HMDMs.

RESULTS

Treatment of PBMCs with either Mtb antigen or with LAB significantly increased the IFN-gamma and NO production. Combination of Mtb antigen and LAB led to synergistic increase in IFN-gamma, and an additive increase in NO. Treatment with Mtb antigen alone significantly increased the IL-4 and IL-13 production. LAB significantly decreased IL-4 and IL-13 secretion in both unstimulated and Mtb antigen-stimulated PBMCs. The IFN-gamma/IL-4+IL-13 ratio was enhanced, indicating Th1/Th2 polarization. Treatment of macrophages with combined use of Mtb antigen and LAB led to an additive increase in Beclin-1, LC3-II expression, as well as in synergistic increase in IL-12 production. Treatment of macrophages with combined use of Mtb antigen and LAB led to a decrease in IL-6, IL-10, and CCL18 secretion. LAB inhibited the secretion of TGF-beta by Mtb-stimulated macrophages, however not significantly. Treatment of macrophages with combined use of Mtb antigen and LAB led to a decrease in CCL18 mRNA expression.

CONCLUSION

Our study implies that LAB may reinforce the response of the mononuclear phagocytes to Mtb antigen by inducing production of the autophagy-promoting factors IFN-gamma and NO, while decreasing the Th2 autophagy-restraining cytokines IL-4 and IL-13. Hence, combination of Mtb antigen and LAB may perhaps be safer in more efficacious TB vaccine formulation.

Lymphocyte subpopulation in healthy and diseased gingival tissue

In this study, infiltrating lymphocytes subpopulation in gingival sections of healthy, inflamed, and periodontitis lesions was investigated. A set of cluster of differentiation (CD) antigen specific monoclonal/polyclonal antibodies to detect different cell types within the tissues was used. These included anti-CD3 (pan T-cell), anti-CD45RO (memory T-cell), anti-CD20 (B-cell), and kappa light chain (plasma cells). Biopsies of gingival tissue were obtained from 17 patients who had clinically healthy gingiva, from 18 patients with gingivitis, and 17 patients with periodontitis.

A significantly greater proportion of T-cells (P < 0.00) was observed in healthy gingival and gingivitis tissue samples compared to periodontitis tissue samples. In addition, a greater proportion of B-cells was observed in periodontitis lesions than in the gingival lesions (P < 0.00). The memory T-cells and the kappa light-chain plasma cells were present in both healthy and diseased tissues, suggestive of previous activation by periodontal pathogenic microorganisms.

In conclusion, these differences in the relative proportions of B- and T-cells may reflect a difference in the immunopathology of periodontitis and gingivitis lesions.

Comparative Analyses of Transcriptional Profiles in Mouse Organs Using a Pneumonic Plague Model after Infection with Wild-Type Yersinia pestis CO92 and Its Braun Lipoprotein Mutant

We employed Murine GeneChips to delineate the global transcriptional profiles of the livers, lungs, and spleens in a mouse pneumonic plague infection model with wild-type (WT) Y. pestis CO92 and its Braun lipoprotein (Δlpp) mutant with reduced virulence. These organs showed differential transcriptional responses to infection with WT Y. pestis, but the overall host functional processes affected were similar across all three tissues. Gene expression alterations were found in inflammation, cytokine signaling, and apoptotic cell death-associated genes. Comparison of WT and Δlpp mutant-infected mice indicated significant overlap in lipopolysaccharide- (LPS-) associated gene expression, but the absence of Lpp perturbed host cell signaling at critical regulatory junctions resulting in altered immune response and possibly host cell apoptosis. We generated a putative signaling pathway including major inflammatory components that could account for the synergistic action of LPS and Lpp and provided the mechanistic basis of attenuation caused by deletion of the lpp gene from Y. pestis in a mouse model of pneumonic plague.

Functional expression of formyl peptide receptor family in human NK cells

We determined the expression of the formyl peptide receptor (FPR) family and the functional roles of the FPR family in NK cells. All tested human NK cells express two members of the FPR family (FPR1 and FPR2). The expression of FPR3 was noted to occur in a donor-specific manner. The stimulation of NK cells with FPR family-selective agonists (fMLF (N-formyl-Met-Leu-Phe), MMK-1, F2L, and WKYMVm (Trp-Lys-Tyr-Met-Val-d-Met)) elicited cytolytic activity in resting NK cells, but not in IL-2-activated NK cells; the cytolytic activity was not inhibited by pertussis toxin. The FPR family agonists also stimulated chemotactic migration of IL-2-activated NK cells, but not resting NK cells; the chemotactic migration was completely inhibited by pertussis toxin. WKYMVm stimulates ERK, p38 MAPK, and JNK activities in both resting and IL-2-activated NK cells. WKYMVm-induced chemotactic migration was partially inhibited by PD98059 (2'-amino-3'-methoxyflavone); however, the inhibition of JNK by its selective inhibitor (SP600125, anthra[1,9-cd]pyrazol-6(2H)-one) dramatically inhibited the WKYMVm-induced cytolytic activity. Furthermore, WKYMVm-induced chemotactic migration and cytolytic activity were partly inhibited by FPR family-selective antagonists (cyclosporin H and WRWWWW). Taken together, our findings indicate that human NK cells express functional members of the FPR family, and in turn the activation of the three members of the FPR receptor family elicit cytolytic activity in NK cells, thus suggesting that the receptors are potentially important therapeutic targets for the modulation of NK cell-mediated immune responses.

Association of tumor necrosis factor alpha and IL-10 promoter polymorphisms with rheumatoid arthritis in North Indian population

Rheumatoid arthritis is a chronic autoimmune disorder associated with altered expression of pro- and anti-inflammatory cytokines in the affected tissues. The aim of this study was to investigate the association between promoter polymorphisms of TNFalpha and IL-10 gene with susceptibility, age of disease onset and disease severity in North Indian patients with rheumatoid arthritis (RA). SNPs at position -308 and -863 of TNF gene and -819/-592 and -1082 position of IL-10 gene were determined in 222 patients and 208 healthy controls using RFLP or ARMS method. Polymorphism TNF -308A was less prevalent among the patients (1.7%) than controls (4.9%; p = 0.01, OR: 0.32, 95% CI: 0.13-0.76). Among female patients, IL-10 -592A allele associated with higher baseline disease activity scores (5.77 +/- 1.99) than -592C (5.57 +/- 1.19; p = 0.04). Female patients carrying allele A of TNFalpha -863 had earlier age of onset of RA (33.99 +/- 9.6 years) than those with allele C (36.15 +/- 11.21 years; p = 0.043). In conclusion, allele A at TNFalpha -308 locus provides protection against RA in North Indian population while another TNF allele A at -863 position had weak association with earlier onset of disease in female patients. On the other hand promoter polymorphisms of IL-10 did not affect susceptibility but polymorphism at -819/-592A was associated with higher disease activity scores at baseline.

Inflammation enhances myeloid-derived suppressor cell cross-talk by signaling through Toll-like receptor 4

Myeloid-derived suppressor cells (MDSC) are potent inhibitors of anti-tumor immunity that facilitate tumor progression by blocking the activation of CD4(+) and CD8(+) T cells and by promoting a type 2 immune response through their production of IL-10 and down-regulation of macrophage production of IL-12. MDSC accumulate in many cancer patients and are a significant impediment to active cancer immunotherapies. Chronic inflammation has been shown recently to enhance the accumulation of MDSC and to increase their suppression of T cells. These findings led us to hypothesize that inflammation contributes to tumor progression through the induction of MDSC, which create a favorable environment for tumor growth. As chronic inflammation also drives type 2 immune responses, which favor tumor growth, we asked if inflammation mediates this effect through MDSC. We find that IL-1beta-induced inflammation increased IL-10 production by MDSC and induces MDSC, which are more effective at down-regulating macrophage production of IL-12 as compared with MDSC isolated from less-inflammatory tumor microenvironments, thereby skewing tumor immunity toward a type 2 response. Inflammation heightens MDSC phenotype by signaling through the TLR4 pathway and involves up-regulation of CD14. Although this pathway is well-recognized in other myeloid cells, it has not been implicated previously in MDSC function. These studies demonstrate that MDSC are an intermediary through which inflammation promotes type 2 immune responses, and they identify the TLR4 pathway in MDSC as a potential target for down-regulating immune suppression and promoting anti-tumor immunity.

The influence of infection early after allogeneic stem cell transplantation on the risk of leukemic relapse and graft-versus-host disease

An infection after allogeneic stem cell transplantation (SCT) can affect the activity of immune cells and increase the level of proinflammatory cytokines. Further, a post-SCT infection may influence the milieu of the graft-versus-leukemia (GVL) effect and graft-versus-host disease (GVHD). We performed a retrospective study of patients with acute leukemia who had undergone allogeneic SCT using the same preparative regimens and bone marrow as the stem cell source to determine if early post-transplant infection was associated with the risk of leukemic relapse and GVHD. The analysis revealed that patients who had a febrile infection (FI) before post-transplant day 21 (FI group) had a lower actuarial probability of leukemic relapse (P < 0.001) and a higher relapse-free survival rate (P = 0.012) than those patients who did not have a FI before post-transplant day 21 (non-FI group). The experience of early post-transplant FI (HR = 0.316; 95% CI = 0.174-0.575; P < 0.001), together with the presence of chronic GVHD and high risk cytogenetics, were independent predictive factors for post-transplant leukemic relapse. The FI group had a trend towards a higher lymphocyte count on post-transplant day 21 than the non-FI group (P = 0.063), despite the delayed recovery of the platelet count and a trend towards delayed recovery of the neutrophil count. These findings suggest that a change in the immunologic network by infectious diseases in the early post-transplant period favors the milieu of the GVL effect. The specific immunologic change during FI, which can potentiate the GVL effect, remains to be determined.

CD14+ cells are required for IL-12 response in bovine blood mononuclear cells activated with Toll-like receptor (TLR) 7 and TLR8 ligands

Single-stranded viral RNA (ssRNA) was recently identified as the natural ligand for TLR7 and TLR8. ssRNA sequences from viruses, as well as their synthetic analogues stimulate innate immune responses in immune cells from humans and mice, but their immunostimulatory activity has not been investigated in ruminants. In the present investigations, we tested whether synthetic RNA oligoribonucleotides (ORN) can activate immune cells from cattle. In vitro incubation of bovine peripheral blood mononuclear cells (PBMCs) with ORN-induced production of IL-12, IFN-gamma and TNF-alpha. No significant induction of IFN-alpha was observed. Depletion of CD14+ cells from PBMC abrogated the IL-12 response and consequently the IFN-gamma response, suggesting that CD14+ cells are required for PBMC immune activation with ORN. Consistent with these findings, the putative receptors for ORN (TLR7 and TLR8) were expressed at higher levels in the CD14+ fraction than the CD14- PBMC fraction. Pre-treatment of PBMC with bafilomycin (an inhibitor of phagosomal acidification) prior to stimulation with ORN abolished the cytokine responses, confirming that the receptor(s) which mediate the ORN-induced responses are intracellular. These results demonstrate for the first time that the TLR7/8 agonist ORN's have strong immune stimulatory effects in cattle, and suggest that further investigation on the potential of TLR7/8 ligands to activate innate and adaptive immune responses in domestic animals are warranted.

Evaluation of breed-dependent differences in the innate immune responses of Holstein and Jersey cows toStaphylococcus aureusintramammary infection

Mastitis is one of the most prevalent diseases of cattle. Various studies have reported breed-dependent differences in the risk for developing this disease. Among two major breeds, Jersey cows have been identified as having a lower prevalence of mastitis than Holstein cows. It is well established that the nature of the initial innate immune response to infection influences the ability of the host to clear harmful bacterial pathogens. Whether differences in the innate immune response to intramammary infections explain, in part, the differential prevalence of mastitis in Holstein and Jersey cows remains unknown. The objective of the current study was to evaluate several parameters of the innate immune response of Holstein and Jersey cows to intramammary infection withStaphylococcus aureus, a common mastitis-inducing pathogen. To control for non-breed related factors that could influence these parameters, all cows were of the same parity, in similar stages of milk production, housed and managed under identical conditions, and experimentally infected and sampled in parallel. The following parameters of the innate immune response were evaluated: acute phase protein synthesis of serum amyloid A and lipopolysaccharide-binding protein; total and differential circulating white blood cell counts; milk somatic cell counts; mammary vascular permeability; milk N-acetyl-beta-d-glucosaminidase (NAGase) activity; and production of the cytokines, interferon (IFN)-γ, interleukin (IL)-12, tumour growth factor(TGF)-α, and TGF-β1. The temporal response of all of these parameters following infection was similar between Holstein and Jersey cows. Further, with the exception of changes in circulating neutrophils and NAGase activity, the overall magnitude of these parameters were also comparable. Together, these data demonstrate that the innate immune response of Holstein and Jersey cows toStaph. aureusintramammary infection remains highly conserved despite previously reported differences in mastitis prevalence, as well as genotypic and phenotypic traits, that exist between the two breeds.

1 Management of Immunocompromised and Infected Animals

This chapter discusses the management of immunocompromized and infected animals. The microbiological quality of laboratory animals is a direct result of colony management practices, and monitoring provides an after-the-fact assessment of the adequacy of those practices. In the case of immunocompromised animals or in infection experiments, however, monitoring for a comprehensive list of micro-organisms is reasonable. The testing of animals usually starts with necropsy and blood sampling for serology, followed by microscopic examination for parasites and sampling of organs for bacteriology, pathology, and, in rare cases, virological examinations. Biological materials represent a high risk, if they originate from or have been propagated in animals. In particular, tumors, viruses, or parasites that are serially passaged in animals often pick up pathogens, and therefore a high percentage of these are contaminated. It has been shown in mice and rats that all preimplantational stages can be revitalized successfully upon freezethaw procedures. For long-term storage, eight-cell stages have been recommended in the chapter, while two-cell stages were considered to be less suitable. One embryo batch (inbred strain) derived from a single pedigree donor pair may be regarded as a prospective breeding nucleus, if one fertile breeding pair is obtained upon revitalization. Assuming an average revitalization rate of 20% (fertile breeders), one embryo batch should contain a minimum number of 10 embryos to obtain at least one breeding pair with a 50% chance of revitalization.

Comparison of Holstein and Jersey innate immune responses to Escherichia coli intramammary infection

Mastitis is one of the most prevalent diseases in cattle and remains among the most costly diseases to the dairy industry. Various surveys have indicated a greater prevalence of and risk for mastitis in Holstein cows than in Jersey cows. The innate immune system comprises the immediate host defense mechanisms that respond to infection, and differences in the magnitude and rapidity of this response are known to influence susceptibility to and clearance of infectious pathogens. The reported differences in the prevalence of mastitis between Holstein and Jersey cows may suggest the occurrence of breed-dependent differences in the innate immune response to intramammary infection. The objective of the current study was to compare the acute phase and cytokine responses of Holstein and Jersey cows following intramammary infection by the bacterial pathogen Escherichia coli, a leading cause of clinical mastitis. All cows in the study were in similar stages of lactation, of the same parity, subjected to the same housing and management conditions, and experimentally infected on the same day with the same inoculum preparation. Before and after infection, the following innate immune parameters were monitored: bacterial clearance; febrile response; induction of the acute phase proteins serum amyloid A and lipopolysaccharide-binding protein; alterations in total and differential white blood cell counts; changes in milk somatic cell counts and mammary vascular permeability; and induction of the cytokines IFN-gamma, IL-1beta, IL-8, IL-12, and tumor necrosis factor-alpha. Overall innate immune responses were similar between the 2 breeds; however, temporal differences in the onset, cessation, and duration of several responses were detected. Despite these differences, intramammary clearance of E. coli was comparable between the breeds. Together, these data demonstrate a highly conserved innate immune response of Holstein and Jersey cows to E. coli intramammary infection.

The first documented case of brucellosis manifested with pancytopenia and capillary leak syndrome

Hematological complications have been frequently associated with acute brucellosis, but pancytopenia is less frequently seen. Also, capillary leak syndrome has been rarely reported in the literature. In this report, we present a case of brucellosis with pancytopenia leading to capillary leak syndrome. A 21-year-old man was admitted to hospital with complaints of a one-month history of weakness, sweats, and fever and he had hepatosplenomegaly and edema over the pretibial areas. Hemogram revealed pancytopenia and biochemical tests revealed moderate hypoalbuminemia, elevations of lactate dehydrogenase and aspartate aminotransferase. He was diagnosed as brucellosis and capillary leak syndrome. He was given doxycycline and rifampicin. The patient's symptoms were resolved after treatment.

CD11b+Ly-6C(hi) suppressive monocytes in experimental autoimmune encephalomyelitis

Innate immune cells may regulate adaptive immunity by balancing different lineages of T cells and providing negative costimulation. In addition, CD11b(+)Gr-1(+) myeloid-derived suppressor cells have been described in tumor, parasite infection, and severe trauma models. In this study, we observe that splenic CD11b(+) cells markedly increase after experimental autoimmune encephalomyelitis (EAE) immunization, and they suppress T cell proliferation in vitro. Although >80% of CD11b(+) cells express varying levels of Gr-1, only a small population of CD11b(+)Ly-6C(high) inflammatory monocytes (IMC) can efficiently suppress T cell proliferation and induce T cell apoptosis through the production of NO. IFN-gamma produced by activated T cells is essential to induce IMC suppressive function. EAE immunization increases the frequencies of IMC in the bone marrow, spleen, and blood, but not in the lymph nodes. At the peak of EAE, IMC represent approximately 30% of inflammatory cells in the CNS. IMC express F4/80 and CD93 but not CD31, suggesting that they are immature monocytes. Furthermore, IMC have the plasticity to up-regulate NO synthase 2 or arginase 1 expression upon different cytokine treatments. These findings indicate that CD11b(+)Ly-6C(high) IMC induced during EAE priming are powerful suppressors of activated T cells. Further understanding of suppressive monocytes in autoimmune disease models may have important clinical implications for human autoimmune diseases.

Mycobacterial infection and atopy in childhood: a systematic review

The epidemiological relation between mycobacterial infection and the prevalence of atopic disease in humans is still unclear. This is in contrast to studies in murine models in which a clear suppression of atopic symptoms was observed after exposure to mycobacteria or mycobacterial products. We therefore wanted to provide a systematic overview of the published literature on the relationship between mycobacterial infection and atopic disease and to evaluate the causal relationship in a meta-analysis. The EMBASE and MEDLINE databases were searched systematically for papers published in the English literature (1966-2005) on the relation between mycobacterial infection and atopic disease. Original observational or interventional studies involving the paediatric population were included. Two authors independently reviewed articles for data on mycobacterial exposure and atopic disease outcome. Any differences were resolved by discussion. Of a total of 1201 hits, 23 studies (19 cross-sectionals, three case-controls and one prospective cohort) met the inclusion criteria. Only a minority of studies (40%) observed an association between mycobacterial infection and the prevalence of atopic disease outcome. In the meta-analysis, only studies containing data on mycobacterial exposure and atopic disease outcome variables were included. Only cross-sectional studies, in which the relation between a positive tuberculin skin test and allergic symptoms was studied, observed statistically significant negative correlation (odds ratio 0.63; 95% confidence interval: 0.51-0.79). The results of this review show that the evidence of the relationship of mycobacterial infection and atopic disease is based on observations of cross-sectional studies. In a meta-analysis, calculations showed a high level of heterogeneity (I(2)) within studies with similar design making it difficult to pool effects. This may partly be explained by differences in the type and definition of mycobacterial infection and lack of uniformity in the definition of atopy. The results show that only a minority of studies in the literature shows any evidence of inverse relationship between mycobacterial exposure and atopic disease outcome. The fact that the present epidemiological evidence on the relationship between mycobacterial infection and the development of atopic disease is based mainly on cross-sectional observational studies indicates the need for population-based prospective studies to address this issue. This issue needs to be addressed in view of recent suggestions to developing mycobacterial-based vaccines against atopic disease in the future.

Monoclonal antibodies to guinea pig interferon-gamma: tools for cytokine detection and neutralization

We have generated polyclonal antisera and monoclonal antibodies against recombinant guinea pig IFN-gamma. These antibodies were used to inhibit the function of IFN-gamma in vitro and to establish a capture ELISA system for the detection and quantitation of this cytokine. Although recombinant protein expressed in E. coli was available in abundance, it was only of limited value to develop a capture ELISA which detects the native cytokine, since only a limited number of monoclonal antibodies reacted both with the recombinant and the native protein. Positive test results in an initial ELISA setup with recombinant IFN-gamma were not predictive for the detection of IFN-gamma from activated T-lymphocytes in the same assay. After evaluating several different combinations of rabbit antisera and monoclonal antibodies, an assay system was established which uses two mouse monoclonal antibodies as capture and detecting reagents. Three of the monoclonal antibodies and the rabbit antisera were able to block the function of guinea pig IFN-gamma when assayed in a luciferase reporter assay.

Destructive periodontitis lesions are determined by the nature of the lymphocytic response

It is now 35 years since Brandtzaeg and Kraus (1965) published their seminal work entitled "Autoimmunity and periodontal disease". Initially, this work led to the concept that destructive periodontitis was a localized hypersensitivity reaction involving immune complex formation within the tissues. In 1970, Ivanyi and Lehner highlighted a possible role for cell-mediated immunity, which stimulated a flurry of activity centered on the role of lymphokines such as osteoclast-activating factor (OAF), macrophage-activating factor (MAF), macrophage migration inhibition factor (MIF), and myriad others. In the late 1970s and early 1980s, attention focused on the role of polymorphonuclear neutrophils, and it was thought that periodontal destruction occurred as a series of acute exacerbations. As well, at this stage doubt was being cast on the concept that there was a neutrophil chemotactic defect in periodontitis patients. Once it was realized that neutrophils were primarily protective and that severe periodontal destruction occurred in the absence of these cells, attention swung back to the role of lymphocytes and in particular the regulatory role of T-cells. By this time in the early 1990s, while the roles of interleukin (IL)-1, prostaglandin (PG) E(2), and metalloproteinases as the destructive mediators in periodontal disease were largely understood, the control and regulation of these cytokines remained controversial. With the widespread acceptance of the Th1/Th2 paradigm, the regulatory role of T-cells became the main focus of attention. Two apparently conflicting theories have emerged. One is based on direct observations of human lesions, while the other is based on animal model experiments and the inability to demonstrate IL-4 mRNA in gingival extracts. As part of the "Controversy" series, this review is intended to stimulate debate and hence may appear in some places provocative. In this context, this review will present the case that destructive periodontitis is due to the nature of the lymphocytic infiltrate and is not due to periodic acute exacerbations, nor is it due to the so-called virulence factors of putative periodontal pathogens.

Role of endogenous IFN-gamma in macrophage programming induced by IL-12 and IL-18

Besides the established role of interleukin-12 (IL-12) and IL-18 on interferon-gamma (IFN-gamma) production by natural killer (NK), T, and B cells, the effects of these cytokines on macrophages are largely unknown. Here, we investigated the role of IL-12/IL-18 on nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) production by CD11b(+) adherent peritoneal cells, focusing on the involvement of endogenously produced IFN-gamma. C57BL/6 cells released substantial amounts of NO when stimulated with IFN-gamma or lipopolysaccharide (LPS), but failed to respond to IL-12 or IL-18 or both. However, IL-12/IL-18 pretreatment was able to program these cells to release 6-8-fold more NO and TNF-alpha in response to LPS or Trypanosoma cruzi stimulation, with NO levels directly correlating with macrophage resistance to intracellular parasite growth. Analysis of IL-12/IL-18-primed cells from mice deficient in IFN-gamma, IFNGR, and IFN regulatory factor-1 (IRF-1) revealed that these molecules were essential for LPS-induced NO release, but TNF-alpha production was IFN-gamma independent. Conversely, the myeloid differentiation factor 88 (MyD88)-dependent pathway was indispensable for IL-12/IL-18-programmed LPS-induced TNF-alpha production, but not for NO release. Contaminant T and NK cells largely modulated the IL-12/IL-18 programming of LPS-induced NO response through IFN-gamma secretion. Nevertheless, a small population of IFN-gamma(+) cells with a macrophage phenotype was also identified, particularly in the peritoneum of chronically T. cruzi-infected mice, reinforcing the notion that macrophages can be an alternative source of IFN-gamma. Taken together, our data contribute to elucidate the molecular basis of the IL-12/IL-18 autocrine pathway of macrophage activation, showing that endogenous IFN-gamma plays an important role in programming the NO response, whereas the TNF-alpha response occurs through an IFN-gamma-independent pathway.

The potential of Mycobacterium to protect against allergy and asthma

The increase in the global incidence of atopic disease and asthma during the past few decades has been ascribed to environmental factors, including the reduction in exposure to serious infections. The hypothetical framework to explain the inverse relationship between infections and atopic disease and asthma has been called the "hygiene hypothesis." Animal and experimental models have identified Mycobacteria as important potential candidates in the hygiene hypothesis by demonstrating that exposure to Mycobacteria or mycobacterial proteins led to subsequent reduction in different atopic manifestations. Although there are epidemiological studies in support, they have not always been consistent. In this review we appraise epidemiologic evidence on the inverse relationship between mycobacterial exposure and atopic disease, explore the immunological mechanisms involved and evidence that this effect may be dose-dependent, and discuss the challenges facing the use of Mycobacteria as vaccine for prevention of atopic disease.

Involvement of mast cells in IL-12/23 p40 production is essential for survival from polymicrobial infections

Interleukin-12 (IL-12), a heterodimeric cytokine (p35/p40) produced mainly from macrophages and dendritic cells, is an important regulator of T-helper 1 cell responses and for host defense. We found that interferon (IFN) consensus sequence binding protein (ICSBP), which is a transcription factor essential for the expression of p40, was expressed in mouse bone marrow-derived mast cells (BMMCs). The transcription levels of p35 and p40 were increased by stimulation of BMMCs with IFN-gamma/lipopolysaccharide (LPS). IL-12 was secreted from BMMCs in response to LPS but not by FcepsilonRI cross-linking. The p40 levels in the peritoneal cavity of mast cell-deficient W/W(v) and W/W(v) reconstituted with p40(-/-) BMMCs were significantly lower than those of WBB6F(1)(+/+) and wild-type (WT) BMMC-reconstituted W/W(v) in the acute septic peritonitis model. The survival rate of W/W(v) reconstituted with p40(-/-) BMMCs was significantly decreased compared to those of WBB6F(1)(+/+) and WT-BMMC-reconstituted W/W(v), which was due to reduced production of IFN-gamma and subsequent impaired activation of neutrophils in the peritoneal cavity. Survival rate of p40(-/-) mice was also restored by adoptive transfer of WT-BMMCs. These results demonstrate that mast cells play a significant role in the production of IL-12 required for host defense. This is the first report to demonstrate that mast cells are a crucial source of functional IL-12.

Prenatal stress has pro-inflammatory consequences on the immune system in adult rats

The in utero environment is critical for initiating the ontogeny of several physiological systems, including the immune surveillance. Yet, little is known about adverse early experiences on the offspring's immunity and vulnerability to disease. The present work aimed at investigating the impact of restraint prenatal stress (PS) on the development and responsiveness of in vitro and in vivo cellular and humoral immunity of male progeny aged 7 weeks and 6 months. In adult 6-month-old rats, we detected increased circulating CD8(+)-expressing and NK cells in PS rats as compared to controls, associated with higher mRNA expression of IFN-gamma. In addition, in vitro stimulation with phytohemagglutinin-A induced an increase in both the proliferation of T lymphocytes and the secretion of IFN-gamma in PS rats. Interestingly, these alterations were undetectable in younger PS rats (7-week old), except for a slight increase in the mRNA expression of several pro-inflammatory cytokines in peripheral blood mononuclear cells. Moreover, in vivo neutralization of IFN-gamma in young rats had no effects in PS group. In conclusion, we report for the first time long-lasting pro-inflammatory consequences of PS in rats.

fliP influences Citrobacter koseri macrophage uptake, cytokine expression and brain abscess formation in the neonatal rat

Citrobacter koseri causes neonatal meningitis frequently complicated with multiple brain abscesses. During C. koseri central nervous system infection in the neonatal rat model, previous studies have documented many bacteria-filled macrophages within the neonatal rat brain and abscesses. Previous studies have also shown that C. koseri is taken up by, survives phagolysosomal fusion and replicates in macrophages in vitro and in vivo. In this study, in order to elucidate genetic and cellular factors contributing to C. koseri persistence, a combinatory technique of differential fluorescence induction and transposon mutagenesis was employed to isolate C. koseri genes induced while inside macrophages. Several banks of mutants were subjected to a series of enrichments to select for gfp : : transposon fusion into genes that are turned off in vitro but expressed when intracellular within macrophages. Further screening identified several mutants attenuated in their recovery from macrophages compared with the wild-type. A mutation within an Escherichia coli fliP homologue caused significant attenuation in uptake and hypervirulence in vivo, resulting in death within 24 h. Furthermore, analysis of the immunoregulatory interleukin (IL)-10/IL-12 cytokine response during infection suggested that C. koseri fliP expression may alter this response. A better understanding of the bacteria-macrophage interaction at the molecular level and its contribution to brain abscess formation will assist in developing preventative and therapeutic strategies.

Effect of granulocyte colony-stimulating factor on IL-12 p40 production during chemotherapy for B-cell lineage non-Hodgkin's lymphoma patients

Interleukin (IL)-12 is a 70-kDa cytokine comprised of two disulfide-linked proteins (p35 and p40) and is essential for the initiation of effective immune response. Granulocyte-colony stimulating factor (G-CSF) affects the balance in the production of anti-inflammatory cytokines. We investigated the serum IL-12 p40 and IL-12 Mix (p40 and p70) production in 28 patients with B-cell lineage non-Hodgkin's lymphoma (NHL) treated with chemotherapy (e.g., CHOP regimen) with or without G-CSF administration and eight healthy volunteers. We found that serum levels of IL-12 p40 (191.2 +/- 150.0 pg/mL) and IL-12 Mix (277.4 +/- 274.5 pg/mL) in the patients before chemotherapy were higher than those in the healthy volunteers (IL-12 p40: 76.4 +/- 25.3 pg/mL, IL-12 Mix: 48.5 +/- 33.4 pg/mL) (P = 0.04 and 0.02, respectively). Next, we examined the serum IL-12 p40 and IL-12 Mix levels in nine patients receiving chemotherapy with administration of G-CSF (CG group, n = 9) and without G-CSF (C group, n = 9). Serum IL-12 p40 and IL-12 Mix levels were decreased on 10 d after chemotherapy in both groups, and those in CG groups were significantly lower than those in C group. These results indicated that administration of G-CSF decreased serum IL-12 p40 and IL-12 Mix levels. Overall survival (OS) at 24 months was not significantly different in the two groups (58.3% in group C vs. 80.0% in group CG, P = 0.67). However, the survival rate of patients at clinical stages III and IV in CG group (n = 6, 66.0%) was significantly better than that of patients in C group (n = 4, 25.0%) (P = 0.02). Long-term administration of G-CSF appears to influence the survival rate by reducing immunosuppressive IL-12 p40 production.

Human T-cell responses to oral streptococci in human PBMC-NOD/SCID mice

We investigated cellular and humoral immune responses to oral biofilm bacteria, including Streptococcus mutans, Streptococcus anginosus, Streptococcus sobrinus, and Streptococcus sanguinis, in NOD/SCID mice immunized with human peripheral blood mononuclear cells (hu-PBMC-NOD/SCID mice) to explore the pathogenicity of each of those organisms in dental and oral inflammatory diseases. hu-PBMC-NOD/SCID mice were immunized by intraperitoneal injections with the whole cells of the streptococci once a week for 3 weeks. FACS analyses were used to determine the percentages of various hu-T cell types, as well as intracellular cytokine production of interleukin-4 and interferon-gamma. Serum IgG and IgM antibody levels in response to the streptococci were also determined by enzyme-linked immunosorbent assay. S. anginosus induced a significant amount of the proinflammatory cytokine interferon-gamma in CD4(+) and CD8(+) T cells in comparison with the other streptococci. However, there was no significant differences between the streptococci in interleukin-4 production by CD4(+) and CD8(+) T cells after inoculation. Further, S. mutans significantly induced human anti-S. mutans IgG, IgG(1), IgG(2), and IgM antibodies in comparison with the other organisms. In conclusion, S. anginosus up-regulated Th1 and Tc1 cells, and S. mutans led to increasing levels of their antibodies, which was associated with the induction of Th2 cells. These results may contribute to a better understanding of human lymphocyte interactions to biofilm bacteria, along with their impact on dental and mucosal inflammatory diseases, as well as endocarditis.

Bovine splenic NK cells synthesize IFN-gamma in response to IL-12-containing supernatants from Babesia bovis-exposed monocyte cultures

The spleen is a critical effector organ functioning, in haemoparasitic diseases like babesiosis, to destroy the pathogen and clear the host of infected erythrocytes. It has an important role in both innate responses and adaptive immune responses. Young calves demonstrate a strong spleen-dependent innate response to an initial infection with Babesia bovis involving the type-1 regulating cytokines IL-12 and IFN-gamma. However, the specific splenic cell types that produce IFN-gamma in response to infection and the cellular factors that regulate the induction have not been fully determined. Splenic NKp46(+) NK cells were identified and purified. They consisted of CD3(-), CD2(+/-), and CD8(+/-) populations. NK cells responded to exogenous IL-12 and IL-18 with the production of IFN-gamma. Functionally, IL-18 served as a potent co-stimulant with IL-12 for IFN-gamma production. Finally, innate IFN-gamma production was induced in splenic NK cells in the presence of supernatants from B. bovis merozoite-exposed monocytes in an IL-12 pathway-dependent manner.

Decreased levels of interleukin-12p40 in the serum of patients with Whipple's disease

BACKGROUND

An impaired production of interleukin (IL)-12 and T cell interferon-gamma (IFN-gamma) of in vitro stimulated monocytes has been discussed as a pathogenic factor in Whipple's disease (WD). It is unclear whether this defect of cellular immunity is translated to the humoral immune system and to serum correlates.

METHODS

We analyzed the serum of 40 patients with Whipple's disease in various degrees of disease activity by sandwich enzyme-linked immunosorbent assay for differences in cytokine and cell adhesion molecule concentrations compared with age- and sex-matched controls.

RESULTS

We observed a highly significant reduction of IL-12p40 levels (patients, 0.18+/-0.05 ng/ml (mean+/-SEM); controls, 3.19+/-0.39 ng/ml; p<0.01) in all stages of disease activity, whereas the concentration of IL-12p70 was comparable with controls. Furthermore, we observed a slight decrease in tumour necrosis factor alpha (TNF-alpha) concentrations in the serum of patients (patients, 6.36+/-0.90 pg/ml; controls, 10.5+/-1.23 pg/ml; p<0,05). The levels of other cytokines such as IFN-gamma, IL-2, IL-13 and transforming growth factor beta, as well as soluble cell adhesion molecules lymphocyte function-associated antigen 3 and intercellular adhesion molecule 1, were not significantly different compared with controls. Levels of immunoglobulin G2 (IgG2) measured in the serum of WD patients were below normal in 24 of 29 patients and were even below the 95% confidence interval in 10 patients.

CONCLUSION

Our data demonstrate a persistent defect of the cellular immune response with decreased serum concentrations of IL-12p40 and TNF-alpha and decreased IgG2 levels in a large group of WD patients. These data support as in vivo finding the results obtained in previous investigations with stimulated monocytes/lymphocytes. The isolated decrease in IL-12p40 may hint at possible defects in the IL-12/IFN-gamma promoter system.

NK cells in gamma-interferon-deficient mice suppress lung innate immunity against Mycoplasma spp

The purpose of this study was to examine the 100-fold difference in mycoplasma levels in lungs of gamma interferon knockout (IFN-gamma(-/-)) mice compared to those seen with wild-type BALB/c mice at 3 days postinfection. NK cells secreted IFN-gamma; however, their cytotoxic granule extracts failed to kill mycoplasma. We found a conundrum: the clearance of organisms was as effective in NK-depleted IFN-gamma(-/-) animals as in wild-type mice (with both IFN-gamma and NK cells). NK(+) IFN-gamma(-/-) animals had high mycoplasma burdens, but, after NK-like cell depletion, mycoplasma numbers were controlled. Essentially, IFN-gamma was important in animals with NK-like cells and unimportant in animals without NK cells, suggesting that IFN-gamma counters deleterious effects of NK-like cells. Impairment of innate immunity in IFN-gamma(-/-) mice was not due to NK-like cell killing of macrophages. The increased levels of inflammatory cytokines and neutrophils in lung fluids of NK(+) IFN-gamma(-/-) mice were reduced after NK cell depletion. In summary, in the murine model that resembles chronic human disease, innate immunity to mycoplasma requires IFN-gamma when there are NK-like cells and the positive effects of IFN-gamma counteract negative effects of NK-like cells. When imbalanced, NK-like cells promote disease. Thus, it was not the lack of IFN-gamma but the presence of a previously unrecognized NK-like cell-suppressive activity that contributed to the higher mycoplasma numbers. It appears that pulmonary NK cells may contribute to the immunosuppressive environment of the lung, but when needed, these dampening effects can be counterbalanced by IFN-gamma. Furthermore, there may be instances where perturbation of this regulatory balance contributes to the susceptibility to and severity of disease.

Immune Response in Human Visceral Leishmaniasis: Analysis of the Correlation Between Innate Immunity Cytokine Profile and Disease Outcome

We investigated the cytokine profile of cells of the innate immune response and its association with active (ACT), asymptomatic (AS) and cured (CUR) human visceral leishmaniasis (VL), as well as noninfected (NI) subjects. The frequency of cytokine-producing cells was determined after short-term in vitro incubation of whole peripheral blood samples with soluble Leishmania antigen (SLA). Our data demonstrated a predominant type 2 cytokine profile in NI and ACT. In NI, we observed an increase of IL-4+ neutrophils, IL-10+ eosinophils besides a decrease of tumour necrosis factor (TNF)-alpha+ eosinophils/monocytes. Yet in ACT, we observed an increase of IL-4+ neutrophils and natural killer (NK) cells and IL-10+ monocytes, a reduced frequency of IL-12+ and IFN-gamma+ eosinophils and lower levels of TNF-alpha+ and IL-12+ monocytes. AS presented a mixed profile, characterized by an increase of IFN-gamma+ neutrophils/eosinophils and NK cells, of IL-12+ eosinophils/monocytes, as well as increase of IL-4+ neutrophils and NK cells and IL-10+ eosinophils/monocytes. In contrast, CUR was characterized by a type 1 response with an increase of IFN-gamma+ neutrophils/eosinophils and NK cells, associated with an increase in IL-12+ monocytes. In conclusion, we show a correlation between innate immune cytokine patterns and clinical status of VL, suggesting that these cells, in addition to other factors, may contribute to the cytokine microenvironment in which Leishmania-specific T cells are primed and to disease outcome.

Assessment of interleukin-12, gamma interferon, and tumor necrosis factor alpha secretion in sera from mice fed with dietary lipids during different stages of Listeria monocytogenes infection

Recent experimental observations have determined that long-chain n-3 polyunsaturated fatty acids suppress immune functions and are involved in the reduction of infectious disease resistance. BALB/c mice were fed for 4 weeks with one of four diets containing either olive oil (OO), fish oil (FO), hydrogenated coconut oil, or a low fat level. Interleukin-12p70 (IL-12p70), gamma interferon (IFN-gamma), and tumor necrosis factor alpha (TNF-alpha) production in the sera of mice fed these diets and challenged with Listeria monocytogenes were determined by enzyme-linked immunosorbent assay. In addition, bacterial counts from spleens of mice were carried out at 24, 72, or 96 h of infection. Here, we quantified an initial diminution of production of both IL-12p70 and IFN-gamma, which appear to play an important role in the reduction of host resistance to L. monocytogenes infection. In addition, an efficient elimination of L. monocytogenes was observed in spleens of mice fed a diet containing OO at 96 h of infection, despite reductions in IL-12p70 and TNF-alpha production, suggesting an improvement of immune resistance. Overall, our results indicate that the initial reduction of both IL-12 and IFN-gamma production before L. monocytogenes infection represents the most relevant event that corroborates the impairment of immune resistance by n-3 polyunsaturated fatty acids during the different stages of infection. However, we speculate that the modulation of other cytokines must be also involved in this response, because the alteration of cytokine production in mice fed an FO diet in a late phase of L. monocytogenes infection was similar to that in mice fed OO, whereas the ability to eliminate this bacterium from the spleen was improved in the latter group.

The bovine innate immune response during experimentally-induced Pseudomonas aeruginosa mastitis

Almost half of all clinical cases of mastitis are caused by Gram-negative bacteria. Among these bacteria, intramammary infection by Pseudomonas aeruginosa remains one of the most refractory to antibiotic therapy. The ability to recognize potentially harmful pathogens whether previously encountered or not, as well as the induction of an initial pro-inflammatory response to these pathogens, are critical components of host innate immunity. Although the innate immune response to another Gram-negative mastitis-causing pathogen, Escherichia coli, has been well-characterized, little is known about the response to other Gram-negative bacteria, including P. aeruginosa. The objective of the current study was to characterize the systemic and localized bovine innate immune response to intramammary infection with P. aeruginosa. The contralateral quarters of ten mid-lactating Holstein cows were challenged with either saline or P. aeruginosa. Following the establishment of infection, milk samples were collected and assayed for changes in cytokine and growth factor concentrations, complement activation, and changes in the levels of soluble CD14 (sCD14) and lipopolysaccharide (LPS)-binding protein (LBP), two accessory molecules involved in host recognition of Gram-negative bacteria. Initial increases in milk somatic cell counts were evident within 12h of experimental challenge and remained elevated for >or=3 weeks. Increased permeability of the mammary gland vasculature, as evidenced by elevated milk levels of BSA, was initially observed 20 h post-infection and persisted for 2 weeks. Within 32 h of challenge, increased levels of IL-8, TNF-alpha, IL-10, and IL-12 were detected, however, the elevated levels of these cytokines were not sustained for longer than a 24h period. In contrast, elevations in IL-1beta, IFN-gamma, TGF-alpha, TGF-beta1, TGF-beta2, sCD14, LBP, and activated complement factor 5 (C5a) were sustained for periods of >48 h. Systemic changes were characterized by elevated body temperature, induction of the acute phase protein synthesis of serum amyloid A and LBP, and a transient decrease in circulating neutrophils and lymphocytes. Together, these data demonstrate the capability of the mammary gland to mount a robust innate immune response to P. aeruginosa that is characterized by the induction of pro-inflammatory cytokines, complement activation, and increased levels of accessory molecules involved in Gram-negative bacterial recognition.

Gamma interferon enhances internalization and early nonoxidative killing of Salmonella enterica serovar Typhimurium by human macrophages and modifies cytokine responses

Gamma interferon (IFN-gamma) is a critical cytokine in host defense against salmonella infections, but its role in phagocytic killing of intracellular Salmonella spp. has been investigated mainly in animal rather than human cells. We measured the effect of recombinant IFN-gamma (rIFN-gamma) priming on bacterial internalization, intracellular killing, oxidative burst, and cytokine release during phagocytosis of Salmonella enterica serovar Typhimurium by human monocyte-derived macrophages (MDM). Eleven-day-old MDM, primed for 72 h with rIFN-gamma (100 ng/ml) exhibited an increased proportion of cells with associated bacteria (31% versus 26%, P = 0.036) and a 67% increase in internalized bacteria per cell compared to unprimed cells (P = 0.025). Retrieval of viable bacteria following internalization was reduced 3.6-fold in 72-h primed versus unprimed MDM (interquartile range, 3.1 to 6.4) at 0.5 h due to enhanced early intracellular killing, and this difference was maintained up to 24 h. In contrast, cells primed for only 24 h exhibited no increase in early killing. MDM were competent to produce an early oxidative burst when stimulated with phorbol myristate acetate, which was fully abrogated by the respiratory burst inhibitor diphenyleneiodonium chloride (DPI), but infection of MDM with S. enterica serovar Typhimurium did not cause an increase in the early respiratory burst under unprimed or primed conditions, and DPI had no effect on the early killing of bacteria by primed or unprimed MDM. During 24 h following infection, rIFN-gamma-primed MDM released more interleukin-12 (IL-12) and less IL-10 relative to unprimed cells. We conclude that 72-h priming with rIFN-gamma increases the efficiency of internalization and nonoxidative early intracellular killing of S. enterica serovar Typhimurium by human macrophages and modifies subsequent cytokine release.

IL-2 induces expression and secretion of IFN-γ in murine peritoneal macrophages

We investigated the effect of interleukin (IL)-2, a T cell growth factor capable of activating certain macrophage functions, on interferon (IFN)-gamma expression in resting mouse peritoneal macrophages (PM). IL-2 addition to PM from different mouse strains up-modulated IFN-gamma mRNA and protein secretion. It is notable that endogenous type I and II IFNs did not play any role in the IL-2-mediated effect, as comparable levels of secreted IFN-gamma were observed upon IL-2 stimulation of PM from deficient mice. In contrast, endogenous IFN-gamma was requested for the IL-12-induced IFN-gamma production. It is interesting that blocking of each component of the IL-2 receptor (IL-2R) by neutralizing antibodies almost completely abolished IL-2-induced IFN-gamma production, suggesting that all IL-2R chains contribute to the PM biological response to IL-2. The simultaneous treatment of PM with IL-2 and IL-12 resulted in a higher IFN-gamma secretion with respect to that obtained upon treatment with IL-2 or IL-12 alone. It is notable that IFN-gamma protein was expressed intracellularly in the majority of cells exhibiting a macrophage phenotype (i.e., F4/80+) and was secreted upon IL-2 stimulation. Overall, these findings demonstrate that IL-2 regulates at different levels IFN-gamma expression in macrophages, highlighting the crucial role of these cells and their regulated responsiveness to key cytokines in the cross-talk between innate and adaptive immunity.

Distinct phases in recovery of reconstituted innate cellular-mediated immunity after murine syngeneic bone marrow transplantation

Defects in immune reconstitution after hematopoietic stem cell transplantation confer extreme infection risk on to the transplant recipient. Perturbations in adaptive immune reconstitution have been well characterized, yet defects in reconstituted innate cellular-mediated immunity remain largely unstudied. Recovery in innate effector cells was defined by using an established murine model of autologous bone marrow transplantation. Cytokine induction after cell culture and systemic stimulation with pathogen-associated molecular patterns was also measured for control, transplant-recipient, and irradiated-only animals. Early reconstitution (7 to 14 days) of donor-derived macrophages, dendritic cells, and polymorphonuclear cells was associated with recovery in interleukin (IL)-12p70 and IL-6 production. Later reconstitution (21 days) of natural killer cells was associated with interferon (IFN)-gamma recovery. Hence, splenocyte innate cellular-mediated immunity recovered to normal levels in cellularity and IL-12p70, IFN-gamma, and IFN-alpha production by 21 days after transplantation. In contrast, levels of systemic cytokine production from transplant-recipient and irradiated-only animals were preserved despite incomplete or absent hematopoietic reconstitution. These results suggest that innate immune responses to systemic inflammatory challenges are largely intact after autologous bone marrow transplantation, whereas local innate cellular-mediated immunity within reconstituting lymphoid organs may be impaired. The disparate effects of autologous hematopoietic stem cell transplantation on host immune function may translate to differences in susceptibility to local versus systemic infectious challenges.

Immunization with cytoplasmic repetitive antigen and flagellar repetitive antigen of Trypanosoma cruzi stimulates a cellular immune response in mice

In previous studies, we demonstrated that CRA and FRA recombinant proteins, used for diagnosis of Chagas' disease, elicited a humoral immune response in susceptible and resistant mice. To understand better the immune response to these proteins, we have evaluated, the cellular immune response in CRA- and in FRA-immunized BALB/c and C57BL/6 mice. A specific cellular lymphoproliferative response was observed in both strains of mice. Spleen cell cultures mainly from CRA-immunized C57BL/6 and FRA-immunized BALB/c mice produced high levels of IFN-y, indicating the induction of a Type 1 immune response. Regarding the T cell subsets, CD4+ T cells were the major source of IFN-y in CRA- and FRA-immunized mice. These results suggest that CRA and FRA are important immunogens in inducing a Type 1 immune response and that they may be considered as potential vaccine antigens.

Effect of dexamethasone on B7 regulation and T cell activation in neonates and adults

The safety of dexamethasone for neonates has been questioned, partly because of its multiple unspecific effects on the immune system. Specific effects of dexamethasone on co-stimulatory and immune suppressive functions of neonatal compared with adult macrophages (MPhi) are not known. We evaluated the effect of dexamethasone on the expression and regulation of MPhi B7 family receptors (B7-1, CD80; B7-2, CD86) and on their ability to co-stimulate T cells. Cord blood macrophages (CBMPhi) and MPhi from healthy adults (PBMPhi) were isolated, and cell surface markers were phenotyped by flow cytometry. In tissue culture, cells were exposed to dexamethasone, interferon-gamma (IFN-gamma), cAMP, or a T cell mitogen (alphaCD3) and examined for their capacity to activate or destroy T cells. CBMPhi were less able to up-regulate CD80 and CD86 than PBMPhi (p < 0.05). Dexamethasone inhibited the up-regulation of CD80, CD86, and HLA-DR on PBMPhi and even more so on CBMPhi (p < 0.05 versus PBMPhi for CD80 and CD86). In the presence of dexamethasone, stimulation with alphaCD3 MAb enhanced cytotoxic functions of PMBMPhi and CB(mu)phi with an increase in deleted T cells, a reduced fraction of enlarged T cells, and an inhibition of T cell CD28 up-regulation, which again were more pronounced with CBMPhi (p < 0.05 versus PBMPhi). In conclusion, neonatal MPhi are exquisitely sensitive to the inhibitory effects of dexamethasone on B7 expression. Although perhaps producing the desired therapeutic effect, dexamethasone may do so in newborns at the expense of a near complete paralysis of MPhi-dependent T cell function.

Immunohistological analysis of Tannerella forsythia-induced lesions in a murine model

Tannerella forsythia has been implicated as a defined periodontal pathogen. In the present study a mouse model was used to determine the phenotype of leukocytes in the lesions induced by subcutaneous injections of either live (group A) or nonviable (group B) T. forsythia. Control mice (group C) received the vehicle only. Lesions were excised at days 1, 2, 4, and 7. An avidin-biotin immunoperoxidase method was used to stain infiltrating CD4+ and CD8+ T cells, CD14+ macrophages, CD19+ B cells, and neutrophils. Hematoxylin and eosin sections demonstrated lesions with central necrotic cores surrounded by neutrophils, macrophages and lymphocytes in both group A and group B mice. Lesions from control mice exhibited no or only occasional solitary leukocytes. In both groups A and B, neutrophils were the dominant leukocyte in the lesion 1 day after injection, the numbers decreasing over the 7-day experimental period. There was a relatively low mean percent of CD4+ and CD8+ T cells in the lesions and, whereas the percent of CD8+ T cells remained constant, there was a significant increase in the percent of CD4+ T cells at day 7. This increase was more evident in group A mice. The mean percent of CD14+ macrophages and CD19+ B cells remained low over the experimental period, although there was a significantly higher mean percent of CD19+ B cells at day 1. In conclusion, the results showed that immunization of mice with live T. forsythia induced a stronger immune response than nonviable organisms. The inflammatory response presented as a nonspecific immune response with evidence of an adaptive (T-cell) response by day 7. Unlike Porphyromonas gingivalis, there was no inhibition of neutrophil migration.

Investigation of the hypothalamo-pituitary-adrenal axis and changes in the size of adrenal glands in acute brucellosis

The aim of the study was to investigate the hypothalamo-pituitary-adrenal (HPA) axis by ACTH stimulation test and the changes in adrenal size in acute brucellosis before and after therapy in a prospective study. Sixteen patients with acute brucellosis and 15 healthy subjects were included in the study during the last two years. Cortisol levels were assessed before, 30 and 60 minutes after ACTH (250 microg i.v.) injection and the size of the adrenals was measured in both groups. Mean basal cortisol levels in the patients before the therapy and after the therapy were 22.1 +/- 6.9 microg/dL and 11.3 +/- 6.0 microg/dL, respectively. The difference was statistically significant (p<0.001). There was also statistically significant difference for basal cortisol levels between the healthy subjects (12.2 +/- 4.6 microg/dL) and the patients before the therapy (p<0.001). Peak cortisol responses to ACTH were higher before the therapy in the patients with acute brucellosis (39.3 +/- 10.7 microg/dL) than in the healthy subjects (30.4 +/- 4.8 microg/dL, p = 0.014). However, there was no significant difference for peak cortisol levels in the patients before and after the therapy (32.7 +/- 8.0 microg/dL). Mean basal cortisol levels and peak cortisol responses to ACTH between the patients after the therapy and the healthy controls were similar. Both the maximum width of the adrenal glands and the width of the adrenal limbs were significantly greater before the therapy compared to healthy subjects and post-treatment period. We concluded that the HPA axis is activated and the adrenal glands are enlarged in acute brucellosis, which is reduced after appropriate therapy.

Lack of antigen-specific tissue remodeling in mice deficient in the macrophage galactose-type calcium-type lectin 1/CD301a

Macrophage galactose-type C-type lectins (MGLs), which were recently named CD301, have 2 homologues in mice: MGL1 and MGL2. MGLs are expressed on macrophages and immature dendritic cells. The persistent presence of granulation tissue induced by a protein antigen was observed in wild-type mice but not in mice lacking an endogenous, macrophage-specific, galactose-type calcium-type lectin 1 (MGL1) in an air pouch model. The anti-MGL1 antibody suppressed the granulation tissue formation in wild-type mice. A large number of cells, present only in the pouch of MGL1-deficient mice, were not myeloid or lymphoid lineage cells and the number significantly declined after administration of interleukin 1 alpha (IL-1alpha) into the pouch of MGL1-deficient mice. Furthermore, granulation tissue was restored by this treatment and the cells obtained from the pouch of MGL1-deficient mice were incorporated into the granulation tissue when injected with IL-1alpha. Taken together, MGL1 expressed on a specific subpopulation of macrophages that secrete IL-1alpha was proposed to regulate specific cellular interactions crucial to granulation tissue formation.

Cytokine and contact-dependent activation of natural killer cells by influenza A or Sendai virus-infected macrophages

NK cells participate in innate immune responses by secreting gamma interferon (IFN-gamma) and by destroying virus-infected cells. Here the interaction between influenza A or Sendai virus-infected macrophages and NK cells has been studied. A rapid, cell-cell contact-dependent production of IFN-gamma from NK cells cultured with virus-infected macrophages was observed. Expression of the MHC class I-related chain B (MICB) gene, a ligand for NK cell-activating receptor NKG2D, was upregulated in virus-infected macrophages suggesting a role for MICB in the activation of the IFN-gamma gene in NK cells. IL12Rbeta2, IL18R and T-bet mRNA synthesis was enhanced in NK cells cultured with virus-infected macrophages. Upregulation of these genes was dependent on macrophage-derived IFN-alpha. In contrast to IL12Rbeta2, expression of WSX-1/TCCR, a receptor for IL27, was reduced in NK cells in response to virus-induced IFN-alpha. In conclusion, these results show that virus-infected macrophages activate NK cells via cytokines and direct cellular interactions and further emphasize the role of IFN-alpha in the activation of innate immunity.

Production of IFN-gamma by CD4 T cells is essential for resolving ehrlichia infection

To address the role of cellular immunity during ehrlichia infection, we have used a newly described model of monocytic ehrlichiosis that results from infection of mice by an ehrlichia that was isolated from an Ixodes ovatus tick (Ixodes ovatus ehrlichia, IOE). Immunocompetent C57BL/6 and BALB/c mice exhibited a dose-dependent susceptibility to IOE infection. Mice infected with a high dose inoculum ( approximately 1000 organisms) exhibited pronounced thrombocytopenia, lymphopenia, anemia, and morbidity within 12 days postinfection. Infection was associated with bacterial colonization of a number of tissues. In contrast, mice infected with a low dose inoculum ( approximately 100 organisms) exhibited only transient disease and were able to resolve the infection. SCID mice were highly susceptible to low-dose infection, indicating that adaptive immunity was required. Resistance to sublethal challenge in both C57BL/6 and BALB/c mice was CD4-, but not CD8-, dependent and required IL-12p40-dependent cytokines, IFN-gamma, and TNF-alpha, but not IL-4. CD4 T cells purified from infected mice proliferated in vitro in response to IOE Ags. T cell proliferation was associated with production of IFN-gamma, and the production of this cytokine by CD4 T cells rescued IFN-gamma-deficient mice from fatal infection. Exogenous IFN-gamma was capable of inducing microbiocidal activity in infected macrophages. The data suggest that classical immune mechanisms involving CD4 cells and type 1 cytokines are responsible for macrophage activation and for elimination of this intracellular bacterial pathogen.

Characterization of the Bovine Innate Immune Response to Intramammary Infection with Klebsiella pneumoniae

Gram-negative bacteria are responsible for almost one-half of the clinical cases of mastitis that occur annually. Of those gram-negative bacteria that induce mastitis, Klebsiella pneumoniae remains one of the most prevalent. Detection of infectious pathogens and the induction of a proinflammatory response are critical components of host innate immunity. The objective of the current study was to characterize several elements of the bovine innate immune response to intramammary infection with Klebsiella pneumoniae. The inflammatory cytokine response and changes in the levels of soluble CD14 (sCD14) and lipopolysaccharide (LPS)-binding protein (LBP), 2 proteins that contribute to host recognition of gram-negative bacteria, were studied. The contralateral quarters of 7 late-lactating Holstein cows were challenged with either saline or K. pneumoniae, and milk and blood samples were collected. Initial increases in the chemoattractants C5a and IL-8, as well as TNF-alpha, were evident in infected quarters within 16 h of challenge and were temporally coincident with increases in milk somatic cells. Augmented levels of TNF-alpha and IL-8 were observed in infected quarters until >48 h postchallenge, respectively. Elevated levels of IL-12, IFN-gamma, and the antiinflammatory cytokine, IL-10, which were first detected between 12 and 20 h postinfection, persisted in infected quarters throughout the study (>96 h). Initial increases in milk LBP and sCD14 were detected 16 and 20 h, respectively, after challenge. Together, these data demonstrate that intramammary infection with K. pneumoniae elicits a host response characterized by the induction of proinflammatory cytokines and elevation of accessory molecules involved in LPS recognition.

Poorer NF-κB signaling by microfilariae in macrophages from BALB/c mice affects their ability to produce cytotoxic levels of nitric oxide to kill microfilariae

Upon activation with microfilariae (mf), macrophages from C57Bl/6 mice showed higher nuclear factor-kappa B (NF-kappa B) but lower activating protein 1 DNA-binding activity as compared to BALB/c macrophages. The C57Bl/6 macrophages produced cytotoxic levels of nitric oxide (NO) to kill Setaria cervi mf as compared to BALB/c macrophages. Inhibition of the NF-kappa B signal by pyrrolidine dithiocarbamate (PDTC) blocked NO production and microfilaricidal activity of C57Bl/6 macrophages and inclusion of the exogenous NO generator (SNP) in the PDTC treated C57Bl/6 macrophage cultures induced mf cytotoxicity. These results underscore that the NF-kappa B signal (induced in response to mf) is important for the NO-mediated microfilaricidal activity of macrophages.

Modulation of cytokine production by some phthalimido-desmuramyl dipeptides and their cytotoxicity

Muramyl dipeptide (MDP) is the smallest bacterial cell wall peptidoglycan component having immunomodulatory activity. In an attempt to obtain MDP derivatives with improved and better defined pharmacological profiles we synthesized a new lipophilic phthalimido-desmuramyl dipeptide, LK 508. This novel MDP analogue and three structurally related phthalimido-desmuramyl dipeptides (LK 413, LK 511 and LK 512) were evaluated immunologically. Their ability to modulate the production of cytokines was measured in vitro by their inclusion in cultures of human peripheral blood mononuclear cells (PBMC) activated by ionomycin and phorbol-12-myristate-13-acetate (PMA). The results were compared with the analogous activity of MDP. All compounds tested are strong up-regulators of IL-12 synthesis. All compounds except LK 512 also stimulated IFNgamma synthesis. LK 508, LK 511 and LK 512 are effective in up-regulating IL-2 production. LK 508 and LK 512 considerably up-regulate the synthesis of IL-4 and IL-10. LK 413 and MDP stimulated the production of Th1 promoting and Th1 (IFNgamma and IL-12) cytokines, while LK 508, LK 511 and LK 512 non-selectively up-regulated the production of both Th1 and Th2-types of (IL-4 and IL-10) cytokines. None of the phthalimido-desmuramyl dipeptides was cytotoxic in vitro against the normal cell line HUVEC (human endothelial cells) thereby indicating their potential for use in vivo.

Escherichia coli and Staphylococcus aureus elicit differential innate immune responses following intramammary infection

Staphylococcus aureus and Escherichia coli are among the most prevalent species of gram-positive and gram-negative bacteria, respectively, that induce clinical mastitis. The innate immune system comprises the immediate host defense mechanisms to protect against infection and contributes to the initial detection of and proinflammatory response to infectious pathogens. The objective of the present study was to characterize the different innate immune responses to experimental intramammary infection with E. coli and S. aureus during clinical mastitis. The cytokine response and changes in the levels of soluble CD14 (sCD14) and lipopolysaccharide-binding protein (LBP), two proteins that contribute to host recognition of bacterial cell wall products, were studied. Intramammary infection with either E. coli or S. aureus elicited systemic changes, including decreased milk output, a febrile response, and induction of the acute-phase synthesis of LBP. Infection with either bacterium resulted in increased levels of interleukin 1beta (IL-1beta), gamma interferon, IL-12, sCD14, and LBP in milk. High levels of the complement cleavage product C5a and the anti-inflammatory cytokine IL-10 were detected at several time points following E. coli infection, whereas S. aureus infection elicited a slight but detectable increase in these mediators at a single time point. Increases in IL-8 and tumor necrosis factor alpha were observed only in quarters infected with E. coli. Together, these data demonstrate the variability of the host innate immune response to E. coli and S. aureus and suggest that the limited cytokine response to S. aureus may contribute to the well-known ability of the bacterium to establish chronic intramammary infection.