The role of inflammatory and anti-inflammatory cytokines in the pathogenesis of human tegumentary leishmaniasis

In tegumentary leishmaniasis caused by Leishmania braziliensis, there is evidence that increased production of IFN-γ, TNF-α and absence of IL-10 is associated with strong inflammatory reaction and with tissue destruction and development of the lesions observed in cutaneous leishmaniasis (CL) and mucosal leishmaniasis (ML). We evaluate the role of regulatory cytokines and cytokine antagonists in the downregulation of immune response in L. braziliensis infection. Peripheral blood mononuclear cells from CL and ML were stimulated with soluble Leishmania antigen in the presence or absence of regulatory cytokines (IL-10, IL-27 and TGF-β) or antagonists of cytokines (α-TNF-α and α-IFN-γ). Cytokines production (IL-10, IL-17, TNF-α and IFN-γ) was measured by ELISA. IL-10 and TGF-β downmodulate TNF-α and IL-17 production, whereas IL-27 had no effect in the production of TNF-α, IFN-γ and IL-17 in these patients. Neutralization of TNF-α decreased IFN-γ level and the neutralization of IFN-γ decreased TNF-α level and increased IL-10 production. This study demonstrate that IL-10 and TGF-β are cytokines that appear to be more involved in modulation of immune response in CL and ML patients. IL-10 might have a protective role, since the neutralization of IFN-γ decreases the production of TNF-α in an IL-10-dependent manner.     

Calcitriol downregulates TNF-α and IL-6 expression in cultured placental cells from preeclamptic women

Placenta is an important source and target of hormones that contribute to immunological tolerance and maintenance of pregnancy. In preeclampsia (PE), placental calcitriol synthesis is low; whereas pro-inflammatory cytokines levels are increased, threatening pregnancy outcome. Previously, we showed that calcitriol inhibits Th-1 cytokines under experimental inflammatory conditions in normal trophoblasts. However, a study of the regulation of inflammatory cytokines by calcitriol in trophoblasts from a natural inflammatory condition, such as PE, is still lacking. Therefore, the aim of the present study was to investigate calcitriol effects upon TNF-α, IFN-γ, IL-6 and IL-1β in cultured placental cells from preeclamptic women by using qPCR and ELISA. Placentas were collected after cesarean section from preeclamptic women and enriched trophoblastic preparations were cultured in the absence or presence of different calcitriol concentrations during 24 h. In these cell cultures, pro-inflammatory cytokines TNF-α and IL-6 secretion and mRNA expression were downregulated by calcitriol (P < 0.05). No significant effects of calcitriol upon IFN-γ and IL-1β were observed. In addition, basal expression of TNF-α, IL-6 and IL-1β decreased as the cells formed syncytia. Our study supports an important autocrine/paracrine role of placental calcitriol in controlling adverse immunological responses at the feto–maternal interface, particularly in gestational pathologies associated with exacerbated inflammatory responses such as preeclampsia.     

Transforming growth factor-β and Th17 responses in resistance to primary murine schistosomiasis mansoni

Discovery of the T-helper (Th) 17 cell lineage and functions in immune responses of mouse and man prompted us to investigate the role of transforming growth factor-beta (TGF-β) and interleukin (IL)-17 in innate resistance to murine schistosomiasis mansoni. Schistosoma mansoni-infected BALB/c and C57BL/6 mice were administered with recombinant TGF-β or mouse monoclonal antibody to TGF-β to evaluate the impact of this cytokine on host immune responses against lung-stage schistosomula, and subsequent effects on adult worm parameters. Developing schistosomula elicited increase in peripheral blood mononuclear cells (PBMC) mRNA expression and/or plasma levels of IL-4, IL-17, and interferon-gamma (IFN-γ), cytokines known to antagonize each other, resulting in impaired Th1/Th2, and Th17 immune responses and parasite evasion. Mice treated with TGF-β showed elevated PBMC mRNA expression of IL-6, IL-17, TGF-β, and TNF-α mRNA and increased IL-23 and IL-17 or TGF-β plasma levels, associated with significantly (P < 0.02–<0.0001) lower S. mansoni adult worm burden compared to controls in both mouse strains, thus suggesting that TGF-β led to heightened Th17 responses that mediated resistance to the infection. Mice treated with antibody to TGF-β showed increase in PBMC mRNA expression and plasma levels of IL-4, IL-12p70, and IFN-γ, and significantly (P < 0.02 and <0.0001) reduced worm burden and liver worm egg counts than untreated mice, indicating that Th1/Th2 immune responses were potentiated, resulting in significant innate resistance to schistosomiasis. The implications of these observations for schistosome immune evasion and vaccination were discussed.     

IL-1RI (interleukin-1 receptor type I) signalling is essential for host defence and hemichannel activity during acute central nervous system bacterial infection

Staphylococcus aureus is a common aetiological agent of bacterial brain abscesses. We have previously established that a considerable IL-1 (interleukin-1) response is elicited immediately following S. aureus infection, where the cytokine can exert pleiotropic effects on glial activation and blood–brain barrier permeability. To assess the combined actions of IL-1α and IL-1β during CNS (central nervous system) infection, host defence responses were evaluated in IL-1RI (IL-1 receptor type I) KO (knockout) animals. IL-1RI KO mice were exquisitely sensitive to intracerebral S. aureus infection, as demonstrated by enhanced mortality rates and bacterial burdens within the first 24 h following pathogen exposure compared with WT (wild-type) animals. Loss of IL-1RI signalling also dampened the expression of select cytokines and chemokines, concomitant with significant reductions in neutrophil and macrophage infiltrates into the brain. In addition, the opening of astrocyte hemichannels during acute infection was shown to be dependent on IL-1RI activity. Collectively, these results demonstrate that IL-1RI signalling plays a pivotal role in the genesis of immune responses during the acute stage of brain abscess development through S. aureus containment, inflammatory mediator production, peripheral immune cell recruitment, and regulation of astrocyte hemichannel activity. Taken in the context of previous studies with MyD88 (myeloid differentiation primary response gene 88) and TLR2 (Toll-like receptor 2) KO animals, the current report advances our understanding of MyD88-dependent cascades and implicates IL-1RI signalling as a major antimicrobial effector pathway during acute brain-abscess formation.     

Lactobacilli Regulate Staphylococcus aureus 161:2-Induced Pro-Inflammatory T-Cell Responses In Vitro

There seems to be a correlation between early gut microbiota composition and postnatal immune development. Alteration in the microbial composition early in life has been associated with immune mediated diseases, such as autoimmunity and allergy. We have previously observed associations between the presence of lactobacilli and Staphylococcus (S.) aureus in the early-life gut microbiota, cytokine responses and allergy development in children. Consistent with the objective to understand how bacteria modulate the cytokine response of intestinal epithelial cell (IEC) lines and immune cells, we exposed IEC lines (HT29, SW480) to UV-killed bacteria and/or culture supernatants (-sn) from seven Lactobacillus strains and three S. aureus strains, while peripheral blood mononuclear cells (PBMC) and cord blood mononuclear cells (CBMC) from healthy donors were stimulated by bacteria-sn or with bacteria conditioned IEC-sn. Although the overall IEC response to bacterial exposure was characterized by limited sets of cytokine and chemokine production, S. aureus 161:2-sn induced an inflammatory response in the IEC, characterized by CXCL1/GROα and CXCL8/IL-8 production, partly in a MyD88-dependent manner. UV-killed bacteria did not induce a response in the IEC line, and a combination of both UV-killed bacteria and the bacteria-sn had no additive effect to that of the supernatant alone. In PBMC, most of the Lactobacillus-sn and S. aureus-sn strains were able to induce a wide array of cytokines, but only S. aureus-sn induced the T-cell associated cytokines IL-2, IL-17 and IFN-γ, independently of IEC-produced factors, and induced up regulation of CTLA-4 expression and IL-10 production by T-regulatory cells. Notably, S. aureus-sn-induced T-cell production of IFN- γ and IL-17 was down regulated by the simultaneous presence of any of the different Lactobacillus strains, while the IEC CXCL8/IL-8 response was unaltered. Thus these studies present a possible role for lactobacilli in induction of immune cell regulation, although the mechanisms need to be further elucidated.     

Interleukin-10 but not Transforming Growth Factor beta inhibits murine activated macrophages Paracoccidioides brasiliensis killing: Effect on H2O2 and NO production

Paracoccidioidomycosis is caused by the thermally dimorphic fungus Paracoccidioides brasiliensis (P. brasiliensis). Most often, this mycosis runs as a chronic progressive course affecting preferentially the lungs. In vitro fungicidal activity against a high virulent strain of P. brasiliensis by murine peritoneal macrophages preactivated with IFN-γ or TNF-α is high and correlates with increased NO and H₂O₂ production. Within this context, the purpose of this work was to study the role of suppressor cytokines, such as IL-10 and TGF-β, in this process. Incubation of either IFN-γ or TNF-α with IL-10 inhibits fungicidal activity of these cells. However, TGF-β had no effect on fungicidal activity of IFN-γ or TNF-α-activated macrophages. The suppression of fungicidal activity by IL-10 correlated with the inhibition of NO and H₂O₂ production supporting the involvement of these metabolites in P. brasiliensis killing. These results suggest that IL-10 production in vivo could represent an evasion mechanism of the fungus to avoid host immune response.     

The role of phagocytosis in IL-8 production by human monocytes in response to lipoproteins on Staphylococcus aureus

Cytokine responses to microbes are triggered by pattern recognition receptors, such as Toll-like receptors (TLRs), which sense pathogen-associated molecular patterns. Cell wall-associated triacylated lipoproteins in Staphylococcus aureus are known to be native TLR2 ligands that mediate host inflammatory responses against S. aureus. However, the mechanism by which these lipidated lipoproteins, which are buried under the thick S. aureus cell wall, work to stimulate TLR2 remains unclear. Heat-killed wild type S. aureus cells activated human monocytic THP-1 cells to produce proinflammatory cytokines, including interleukin (IL)-8, whereas the lipoprotein lipidation-deficient lgt mutant induced less than an eighth of the amount of IL-8 induced by the wild type. IL-8 induction in response to heat-killed S. aureus cells in THP-1 cells was not inhibited by a blocking antibody against cell surface TLR2, suggesting that intracellular TLR2 might be involved in the induction of IL-8 by S. aureus lipoprotein. The relationship between phagocytosis and IL-8 production in THP-1 cells was analyzed on a single-cell level by flow cytometry using fluorescein-labeled S. aureus cells and phycoerythrin-labeled anti-IL-8 antibody. Production of intracellular IL-8 was correlated with phagocytosis of S. aureus cells in THP-1 cells and in human peripheral blood mononuclear cells. Opsonization of S. aureus cells enhanced both the phagocytosis of S. aureus cells and the production of intracellular IL-8 in THP-1 cells. These results suggest that lipidated lipoproteins on S. aureus cells stimulate human monocytes after phagocytosis.     

Staphylococcus aureus Alpha Toxin Suppresses Effective Innate and Adaptive Immune Responses in a Murine Dermonecrosis Model

An optimal host response against Staphylococcus aureus skin and soft tissue infections (SSTI) is dependent on IL-1β and IL-17 mediated abscess formation. Alpha toxin (AT), an essential virulence factor for SSTI, has been reported to damage tissue integrity; however its effect on the immune response has not been investigated. Here, we demonstrate that infection with USA300 AT isogenic mutant (Δhla), or passive immunization with an AT neutralizing mAb, 2A3, 24 h prior to infection with wild type USA300 (WT), resulted in dermonecrotic lesion size reduction, and robust neutrophil infiltration. Infiltration correlates with increase in proinflammatory cytokines and chemokines, as well as enhanced bacterial clearance relative to immunization with a negative control mAb. In addition, infection with Δhla, or with WT +2A3, resulted in an early influx of innate IL-17⁺γδT cells and a more rapid induction of an adaptive immune response as measured by Th1 and Th17 cell recruitment at the site of infection. These results are the first direct evidence of a role for AT in subverting the innate and adaptive immune responses during a S. aureus SSTI. Further, these effects of AT can be overcome with a high affinity anti-AT mAb resulting in a reduction in disease severity.     

Expression analysis of immune response genes in fish epithelial cells following ranavirus infection

Ranaviruses (family Iridoviridae) are a growing threat to fish and amphibian populations worldwide. The immune response to ranavirus infection has been studied in amphibians, but little is known about the responses elicited in piscine hosts. In this study, the immune response and apoptosis induced by ranaviruses were investigated in fish epithelial cells. Epithelioma papulosum cyprini (EPC) cells were infected with four different viral isolates: epizootic haematopoietic necrosis virus (EHNV), frog virus 3 (FV3), European catfish virus (ECV) and doctor fish virus (DFV). Quantitative real-time PCR (qPCR) assays were developed to measure the mRNA expression of immune response genes during ranavirus infection. The target genes included tumour necrosis factor α (TNF-α), interleukin-1β (IL-1β), β2-microglobulin (β2M), interleukin-10 (IL-10) and transforming growth factor β (TGF-β). All ranaviruses elicited changes in immune gene expression. EHNV and FV3 caused a strong pro-inflammatory response with an increase in the expression of both IL-1β and TNF-α, whereas ECV and DFV evoked transient up-regulation of regulatory cytokine TGF-β. Additionally, all viral isolates induced increased β2M expression as well as apoptosis in the EPC cells. Our results indicate that epithelial cells can serve as an in vitro model for studying the mechanisms of immune response in the piscine host in the first stages of ranavirus infection.     

Burn-induced alterations in toll-like receptor-mediated responses by bronchoalveolar lavage cells

Burn is associated with profound inflammation and activation of the innate immune system in multiple organ beds, including the lung. Similarly, toll-like receptors (TLR) are associated with innate immune activation. Nonetheless, it is unclear what impact burn has on TLR-induced inflammatory responses in the lung.MethodsMale C57BL/6 mice were subjected to burn (3rd degree, 25% TBSA) or sham procedure and 1, 3 or 7 days thereafter, bronchoalveolar lavage (BAL) fluid was collected and cells were isolated and cultured in vitro with specific TLR agonists as follows: Zymosan (TLR-2), LPS (TLR-4) and CpG-ODN (TLR-9). Supernatants were collected 48 h later and assayed for inflammatory cytokine levels (IL-1β, IL-6, IL-10, IL-17, TNF-α, KC, MCP-1, MIP-1α, MIP-1β and RANTES) by Bioplex.ResultsBAL fluid from sham and burn mice did not contain detectable cytokine levels. BAL cells, irrespective of injury, were responsive to TLR-2 and TLR-4 activation. Seven days after burn, TLR-2 and TLR-4 mediated responses by BAL cells were enhanced as evidenced by increased production of IL-6, IL-17, TNF-α, MCP-1, MIP-1β and RANTES.ConclusionsBurn-induced changes in TLR-2 and TLR-4 reactivity may contribute to the development of post-burn complications, such as acute lung injury (ALI) and adult respiratory distress syndrome (ARDS).     

Reciprocal induction of tumor necrosis factor-α and interleukin-β activity mediates fibronectin synthesis in coronary artery smooth muscle cells

We previously demonstrated an immune-inflammatory response associated with increased expression of interleukin (IL)-β and fibronectin in graft coronary arteriopathy in piglets following heterotopic heart transplant. Further studies showed that increased endogenously produced IL-β was upregulating fibronectin production by donor coronary artery (CA) smooth muscle cells (SMC). Since co-induction of IL-β and tumor necrosis factor (TNF)-α has been shown in other systems, we investigated the possible interaction between these cytokines in regulating fibronectin production in CA SMC. First, we documented increased TNF-α expression in vivo in donor compared to host CA. Next, synthesis of fibronectin was measured in host and donor CA SMC following [³⁵S]-methionine radiolabeling and gelatin-sepharose extraction. As previously shown with IL-β, increased donor CA SMC fibronectin synthesis was reduced to host levels in the presence of TNF-α antibodies, and exogenous TNF-α upregulated fibronectin synthesis in host CA SMC to levels in donor cells. In normal CA SMC, TNF-α-stimulated fibronectin production was downregulated to or below control levels in the presence of IL-β antibodies. Likewise, IL-β-stimulated fibronectin synthesis was downregulated to control levels when TNF-α neutralizing antibodies were added. Combining TNF-α and IL-β enhanced fibronectin production over that observed with either cytokine alone, but was not additive. Thus, our studies suggest that vascular SMC fibronectin synthesis is regulated by reciprocal induction of IL-β and TNF-α activity and provide the first demonstration of a ‘cytokine loop’ modulating matrix production. © 1995 Wiley-Liss, Inc.     

Lipopolysaccharide from Rhodobacter capsulatus counteracts the effects of toxic lipopolysaccharides and inhibits the release of TNF-α, IL-6, and IL-1β in human whole blood

The outcome of pathological process during sepsis caused by Gram-negative bacteria depends on the reaction of human blood cells to bacterial structural components, lipopolysaccharides (LPS). A general inflammatory response develops due to the increased production of proinflammatory cytokines. One of the current methods of prevention of inflammatory response is the inhibition of LPS binding to cellular receptors. We have studied the efficacy of antagonistic properties of LPS from Rhodobacter capsulatus on the production of TNF-α, IL-6, and IL-1β cytokines induced by toxic LPS from Salmonella typhimurium and Escherichia coli in human whole blood. LPS from R. capsulatus in concentrations of 0.1 and 1 μg/mL did not induce synthesis of TNF-α, IL-6, or IL-1β. Measurements of cytokine levels showed that LPS from R. capsulatus exerted a clear protective effect against toxic LPS. In particular, LPS from R. capsulatus fullly inhibited the production of TNF-α and IL-1β and significantly decreased the IL-6 production induced by LPS from S. typhimurium. Additionally, LPS from R. capsulatus antagonized the effects of LPS from E. coli, fully inhibiting the TNF-α production and decreasing the IL-6 and IL-1β levels by 60% and 70%, respectively. Thus, LPS from R. capsulatus acts as a potent antagonist of cell activation induced by toxic LPS.     

Effects of Small Intestinal Submucosa (SIS) on the Murine Innate Immune Microenvironment Induced by Heat-Killed Staphylococcus aureus

The use of biological scaffold materials for wound healing and tissue remodeling has profoundly impacted regenerative medicine and tissue engineering. The porcine-derived small intestinal submucosa (SIS) is a licensed bioscaffold material regularly used in wound and tissue repair, often in contaminated surgical fields. Complications and failures due to infection of this biomaterial have therefore been a major concern and challenge. SIS can be colonized and infected by wound-associated bacteria, particularly Staphylococcus aureus. In order to address this concern and develop novel intervention strategies, the immune microenvironment orchestrated by the combined action of S. aureus and SIS should be critically evaluated. Since the outcome of tissue remodeling is largely controlled by the local immune microenvironment, we assessed the innate immune profile in terms of cytokine/chemokine microenvironment and inflammasome-responsive genes. BALB/c mice were injected intra-peritoneally with heat-killed S. aureus in the presence or absence of SIS. Analyses of cytokines, chemokines and microarray profiling of inflammasome-related genes were done using peritoneal lavages collected 24 hours after injection. Results showed that unlike SIS, the S. aureus-SIS interactome was characterized by a Th1-biased immune profile with increased expressions of IFN-γ, IL-12 and decreased expressions of IL-4, IL-13, IL-33 and IL-6. Such modulation of the Th1/Th2 axis can greatly facilitate graft rejections. The S. aureus-SIS exposure also augmented the expressions of pro-inflammatory cytokines like IL-1β, Tnf-α, CD30L, Eotaxin and Fractalkine. This heightened inflammatory response caused by S. aureus contamination could enormously affect the biocompatibility of SIS. However, the mRNA expressions of many inflammasome-related genes like Nlrp3, Aim2, Card6 and Pycard were down-regulated by heat-killed S. aureus with or without SIS. In summary, our study explored the innate immune microenvironment induced by the combined exposure of SIS and S. aureus. These results have practical implications in developing strategies to contain infection and promote successful tissue repair.     

<Emphasis Type="Italic">Brucella abortus</Emphasis> phosphoglyceromutase and dihydrodipicolinate reductase induce Th1 and Th2-related immune responses

Brucellae are intracellular bacterial pathogens that cause Brucellosis, bringing great economic burdens to developing countries. The pathogenic mechanisms of Brucella are still poorly understood. Earlier immune response plays an important role in the Brucella infection. Phosphoglyceromutase (PGM) and dihydrodipicolinate reductase (DapB) were cloned, expressed, purified, and their immunocompetence was analyzed. Cytokines were detected by murine macrophages (RAW 264.7) and splenocytes that stimulated with the two recombinant proteins. The immune responses were analyzed by ELISA from mice with the two recombinant proteins immunized. TNF-α, IL-6 and IL-8 were produced in stimulated RAW 264.7 cells and splenocytes. Th1-type cytokines, IFN-γ and IL-2, induced in RAW 264.7 cells and splenocytes were higher then Th2-type cytokines, IL-4 and IL-5. Th2-related immune response was induced in splenocytes obtained 35 days after mice immunized with the two proteins. The production of IgG1 was higher than IgG2a in immunized mice. Taken together, our results demonstrated that the two proteins could induce Th1 and Th2-type immune responses in vivo and in vitro.     

Shiga toxins expressed by human pathogenic bacteria induce immune responses in host cells

Shiga toxins are a family of genetically and structurally related toxins that are the primary virulence factors produced by the bacterial pathogens Shigella dysenteriae serotype 1 and certain Escherichia coli strains. The toxins are multifunctional proteins inducing protein biosynthesis inhibition, ribotoxic and ER stress responses, apoptosis, autophagy, and inflammatory cytokine and chemokine production. The regulated induction of inflammatory responses is key to minimizing damage upon injury or pathogen-mediated infections, requiring the concerted activation of multiple signaling pathways to control cytokine/chemokine expression. Activation of host cell signaling cascades is essential for Shiga toxin-mediated proinflammatory responses and the contribution of the toxins to virulence. Many studies have been reported defining the inflammatory response to Shiga toxins in vivo and in vitro, including production and secretion of tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), macrophage inflammatory protein-1α/β (MIP-1α/β), macrophage chemoattractant monocyte chemoattractant protein 1 (MCP-1), interleukin 8 (IL-8), interleukin 6 (IL-6), and Groβ. These cytokines and chemokines may contribute to damage in the colon and development of life threatening conditions such as acute renal failure (hemolytic uremic syndrome) and neurological abnormalities. In this review, we summarize recent findings in Shiga toxin-mediated inflammatory responses by different types of cells in vitro and in animal models. Signaling pathways involved in the inflammatory responses are briefly reviewed.     

IL-25, IL-33 and TSLP receptor are not critical for development of experimental murine malaria

IL-25, IL-33 and TSLP, which are produced predominantly by epithelial cells, can induce production of Th2-type cytokines such as IL-4, IL-5 and/or IL-13 by various types of cells, suggesting their involvement in induction of Th2-type cytokine-associated immune responses. It is known that Th2-type cytokines contribute to host defense against malaria parasite infection in mice. However, the roles of IL-25, IL-33 and TSLP in malaria parasite infection remain unclear. Thus, to elucidate this, we infected wild-type, IL-25^?/?, IL-33^?/? and TSLP receptor (TSLPR)^?/? mice with Plasmodium berghei (P. berghei) ANKA, a murine malaria strain. The expression levels of IL-25, IL-33 and TSLP mRNA were changed in the brain, liver, lung and spleen of wild-type mice after infection, suggesting that these cytokines are involved in host defense against P. berghei ANKA. However, the incidence of parasitemia and survival in the mutant mice were comparable to in the wild-type mice. These findings indicate that IL-25, IL-33 and TSLP are not critical for host defense against P. berghei ANKA.     

Combinatory responses of proinflamamtory cytokines on nitric oxide-mediated function in mouse calvarial osteoblasts

Combinatory responses of proinflamamtory cytokines have been examined on the nitric oxide-mediated function in cultured mouse calvarial osteoblasts. Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) induced iNOS gene expression and NO production, although these actions were inhibited by L-NG-monomethylarginine (L-NMMA) and decreased alkaline phosphatase (ALPase) activity. Furthermore, NO donors, sodium nitroprusside (SNP) and NONOate dose-dependently elevated ALPase activity. In contrast, transforming-growth factor-β (TGF-β) decreased NO production stimulated by IL-1β, TNF-α and interferon-γ (IFN-γ). iNOS was expressed by mouse calvarial osteoblast cells after stimulation with IL-1β, TNF-α, and IFN-γ. Incubation of mouse calvarial osteoblast cells with the cytokines inhibited growth and ALPase activity. However, TGF-β-treatment abolished these effects of IL-1β, TNF-α and IFN-γ on growth inhibition and stimulation of ALPase in mouse calvarial osteoblast cells. In contrast, IL-1β, TNF-α, and IFN-γ exerted growth-inhibiting effects on mouse calvarial osteoblast cells which were partly NO-dependent. The results suggest that NO may act predominantly as a modulator of cytokine-induced effects on mouse calvarial osteoblast cells and TGF-β is a negative regulator of the NO production stimulated by IL-1β, TNF-α and IFN-γ.     

Baculovirus activates murine dendritic cells and induces non-specific NK cell and T cell immune responses

We previously reported that the baculovirus induced a strong host immune response against infections and malignancies. Among the immune cells, the dendritic cells were most strongly infected and activated by the baculovirus, although the exact mechanism remained unclear. Here, we evaluated the non-specific immune responses of bone marrow-derived dendritic cells (BMDCs) after infection by a wild-type baculovirus. MHC class I and II molecules and co-stimulation molecules (CD40, CD80, and CD86) on BMDCs were up-regulated by baculovirus infection. At the same time, the BMDCs produced pre-inflammatory cytokines (IL-6, IL12p70, and TNF-α) and IFN-α. NK cells showed IFN-γ production, CD69 up-regulation, and enhanced cytotoxicity when they were co-cultured with baculovirus-infected BMDCs. T cells showed IFN-γ production, CD69 up-regulation, and cell proliferation. Ex vivo analysis performed in vitro produced similar results. These findings suggested that baculovirus-infected dendritic cells induce non-specific immune responses and can be used as an immunotherapeutic agent against viral infections and malignancies, together with present therapeutic drug regimens.