Requirement of scavenger receptors for activation of the IRF-3/IFN-β/STAT-1 pathway in TLR4-mediated production of NO by LPS-activated macrophages

Production of nitric oxide (NO) by LPS-activated macrophages is due to a complex cellular signaling initiated by TLR4 that leads to the transcription of IFN-β, which activates IRF-1 and STAT-1, as well as to the activation of NF-κB, required for iNOS transcription. High concentrations of LPS can also be uptaken by scavenger receptors (SRs), which, in concert with TLR4, leads to inflammatory responses. The mechanisms by which TLR4 and SRs interact, and the pathways activated by this interaction in macrophages are not elucidated. Therefore, our main goal was to evaluate the role of SRs, particularly SR-A, in LPS-stimulated macrophages for NO production. We first showed that, surprisingly, LPS can induce the expression of iNOS and the production of NO in TLR4^-/- mice, provided exogenous IFN-β is supplied. These results indicate that LPS stimulate receptors other than TLR4. The inhibition of SR-A using DSS or neutralizing antibody to SR-AI showed that SR-A is essential for the expression of iNOS and NO production in stimulation of TLR4 by LPS. The restoration of the ability to express iNOS and produce NO by addition of rIFN-β to inhibited SR-A cells indicated that the role of SR-AI in LPS-induced NO production is to provide IFN-β, probably by mediating the internalization of LPS/TLR4, and the differential inhibition by DSS and neutralizing antibody to SR-AI suggested that other SRs are also involved. Our results reinforce that TLR4 and SR-A act in concert in LPS activation and demonstrated that, for the production of NO, it does mainly by synthesizing IRF-3 and also by activating the TRIF/IRF-3 pathway for IFN-β production, essential for LPS-mediated transcription of iNOS. Consequently STAT-1 is activated, and IRF-1 is expressed, which together with NF-κB from TLR4/MyD88/TIRAP, induce iNOS synthesis and NO production. SUMMARY SENTENCE: TLR4 and SRs act in concert activating IRF-3 to transcribe IFN-β and activate STAT-1 to produce NO by LPS-activated macrophages.

The response of Mesenchymal Stem Cells to endodontic materials

An endodontic material must be minimally harmful to stem cells since they are essential, thanks to their capacity for cell proliferation, self-renewal, and differentiation. For this reason, in this in vitro study, the cell viability and the expression of genes involved in cell plasticity and differentiation were investigated in stem cells recovered from human dental pulp (hDPSCs) that were in contact with four endodontic materials (Endofill, MTA, Pulp Canal Sealer, and Sealer 26). The viability of HDPSCs was assessed by MTT and trypan blue exclusion assays. PCR evaluated cellular plasticity by determining the CD34, CD45, Nestin, CD105, Nanog, and OCT4 expressions. The effect on cell differentiation was determined by RT-PCR expression of the RUNX2, ALP, OC/BGLAP, and DMP1 genes. The data were analyzed using ANOVA with Bonferroni correction (p <0.05). Pulp Canal Sealer and Endofill decreased cell viability after 48 hours (p <0.001). MTA and Sealer 26 did not disrupt cell viability (p> 0.05). When cultivated in the presence of MTA and Sealer 26, hDPSCs expressed Nestin, CD105, NANOG, and OCT-4 and did not express CD34 and CD45. MTA and Sealer 26 interfered with DMP1, OC/BGLAP and RUNX2 expressions (p <0.05) but did not change ALP gene expression (p> 0.05). MTA and Sealer 26 showed biological compatibility in the presence of hDPSCs.

Cytotoxicity of two self-adhesive resin cements and their interference in the phagocytic activity of murine macrophages

Objectives

This study aimed to evaluate in vitro the effects of the self-adhesive resin cements RelyX U200 (3M ESPE) and seT PP (SDI Limited) on murine macrophages and the interference of the photoactivation.

Materials and Methods

Cell viability assays, cell adherence, yeast phagocytosis of Saccharomyces boulardii and production of reactive oxygen species (ROS) were performed in the presence of capillaries containing the respective self-adhesive cement when photoactivated or not.

Results

After long periods of contact, both types of cements, when not photoactivated, are more cytotoxic for macrophages. The seT PP cement when only chemically activated seems to interfere more negatively in the process of phagocytosis of yeasts S. boulardii. Both types of cements interfere in the cell adhesion process, independent of photoactivation. None of the types of cements tested was able to induce the production of ROS.

Conclusions

Our results highlight the great importance of the photoactivation of self-adhesive resin cements in the dental clinic, since RelyX U200, when photoactivated, presented the best results within the evaluated parameters.

Resistance Against Leishmania major Infection Depends on Microbiota-Guided Macrophage Activation

Innate immune cells present a dual role during leishmaniasis: they constitute the first line of host defense but are also the main host cells for the parasite. Response against the infection that results in the control of parasite growth and lesion healing depends on activation of macrophages into a classical activated phenotype. We report an essential role for the microbiota in driving macrophage and monocyte-derived macrophage activation towards a resistance phenotype against Leishmania major infection in mice. Both germ-free and dysbiotic mice showed a higher number of myeloid innate cells in lesions and increased number of infected cells, mainly dermal resident and inflammatory macrophages. Despite developing a Th1 immune response characterized by the same levels of IFN-γ production as the conventional mice, germ-free mice presented reduced numbers of iNOS+ macrophages at the peak of infection. Absence or disturbance of host microbiota impaired the capacity of bone marrow-derived macrophage to be activated for Leishmania killing in vitro, even when stimulated by Th1 cytokines. These cells presented reduced expression of inos mRNA, and diminished production of microbicidal molecules, such as ROS, while presenting a permissive activation status, characterized by increased expression of arginase I and il-10 mRNA and higher arginase activity. Colonization of germ-free mice with complete microbiota from conventional mice rescued their ability to control the infection. This study demonstrates the essential role of host microbiota on innate immune response against L. major infection, driving host macrophages to a resistance phenotype.

Selenium intracanal dressing: effects on the periapical immune response

OBJECTIVES

To evaluate the selenium (Se) behavior when used as an endodontic dressing in teeth with pulp necrosis. Additionally, its effects was also compared with the calcium hydroxide (C.H.), which is used globally as a root canal dressing, and the combination of the C.H. with Se (C.H. + Se).

MATERIALS AND METHODS

The sample consisted of 60 patients requiring endodontic treatment who were divided into groups, i.e., without intracanal medication (empty) and with medications as follows: selenium (Se), calcium hydroxide (C.H.), and calcium hydroxide + selenium (C.H. + Se) (n = 15). After the coronary opening, three absorbent paper points were placed in the RCS and maintained for 2 min for microbial evaluation. Following the cleaning and shaping procedures, new paper points were introduced into the root canal system, passing passively through the root apex (2 mm) into the periapical tissues for 2 min, for immune evaluation. The collections were performed again 15 days later. Real-time PCR quantified the expression of the prokaryotic 16S ribosomal RNA. The 16S mRNA was evaluated before the cleaning and shaping procedures and 15 days later in the groups treated with or without medication.

RESULTS

A significant reduction in the microbial load was observed only in the groups that received endodontic dressing (p < 0.05). The cytokines IFN-γ, TNF-α, IL-1α, IL-17A, IL-10, IL-6 and MCP-1, were also quantified by real-time PCR. There was an increase in the gene expression level of the cytokines (T15) TNF-α and IL-10 in the C.H. group compared to the other groups (p < 0.05). The IFN-γ mRNA expression was reduced in the groups treated with the medications (Se, C.H., and C.H. + Se).

CONCLUSIONS

The findings of the present study indicate that in the case of treatment over multiple sessions, the use of root canal dressing is essential to avoid the root canal system (RCS) microbial recolonization. Selenium potentiated the effects of calcium hydroxide inducing an anti-inflammatory response in periapical tissues.

CLINICAL RELEVANCE

Se is a mineral essential for the formation of the amino acid selenocysteine, which is directly involved in the maintenance of the immune response. Selenium has been widely used in the medical field in the treatment of cancer, as an activator of bone metabolism, and as a stimulator of the immune system. In this study, it was shown that the incorporation of Se, whether as intracanal medication alone or in conjunction with other medications, may potentiate periapical tissue repair after RCS cleaning and shaping procedures.

Mineral trioxide aggregate (MTA) inhibits osteoclastogenesis and osteoclast activation through calcium and aluminum activities

OBJECTIVE

To evaluate the effect(s) of mineral trioxide aggregate (MTA) on in vitro RANKL-mediated osteoclast-dependent bone resorption events and the influence of Ca²⁺ and Al³⁺ on the osteoclastogenesis inhibition by MTA.

MATERIALS AND METHODS

Two types of osteoclast precursors, RAW 264.7 (RAW) cell line or bone marrow cells (obtained from BALB/c mice and stimulated with recombinant (r) macrophage colony stimulation factor (M-CSF), were stimulated with or without recombinant (r) activator of nuclear kappa B ligand (RANKL), in the presence or absence of MTA for 6 to 8 days. White Angelus MTA and Bios MTA (Angelus, Londrina, Paraná, Brazil) were prepared and inserted into capillary tubes (direct contact surface = 0.50 mm² and 0.01 mm²). Influence of MTA on these types of osteoclast precursors was measured by the number of differentiated tartrate-resistant acid phosphatase (TRAP)-positive multinuclear cells (RAW and bone marrow cells), TRAP enzyme activity (RAW cells), cathepsin K gene expression (RAW cells), and resorptive pit formation (RAW cells) by mature osteoclasts. Besides, RAW cells were also stimulated with Ca²⁺ and Al³⁺ to evaluate the influence of these ions on MTA anti-osteoclastogenic potential.

RESULTS

In bone marrow and RAW cells, the number of TRAP-positive mature osteoclast cells induced by rRANKL was significantly inhibited by the presence of MTA compared with control rRANKL stimulation without MTA (p < 0.05), along with the reduction of TRAP enzyme activity (p < 0.05) and the low expression of cathepsin K gene (p < 0.05). In contrast, to control mature osteoclasts, the resorption area on dentin was significantly decreased for mature osteoclasts incubated with MTA (p < 0.05). rRANKL-stimulated RAW cells treated with Ca²⁺ and Al³⁺ decreased the number of osteoclasts cells. Besides, the aluminum oxide was the dominant suppressor of the osteoclastogenesis process.

CONCLUSIONS

MTA significantly suppressed RANKL-mediated osteoclastogenesis and osteoclast activity and, therefore, appears able to suppress bone resorption events in periapical lesions. This process might be related to Ca²⁺ and Al³⁺ activities.

CLINICAL RELEVANCE

MTA is an important worldwidely acknowleged biomaterial. The knowledge about its molecular activities on osteoclasts might contribute to improving the understanding of its clinical efficacy.

Chronic ethanol consumption compromises neutrophil function in acute pulmonary Aspergillus fumigatus infection

Chronic ethanol consumption is a leading cause of mortality worldwide, with higher risks to develop pulmonary infections, including Aspergillus infections. Mechanisms underlying increased susceptibility to infections are poorly understood. Chronic ethanol consumption induced increased mortality rates, higher Aspergillus fumigatus burden and reduced neutrophil recruitment into the airways. Intravital microscopy showed decrease in leukocyte adhesion and rolling after ethanol consumption. Moreover, downregulated neutrophil activation and increased levels of serum CXCL1 in ethanol-fed mice induced internalization of CXCR2 receptor in circulating neutrophils. Bone marrow-derived neutrophils from ethanol-fed mice showed lower fungal clearance and defective reactive oxygen species production. Taken together, results showed that ethanol affects activation, recruitment, phagocytosis and killing functions of neutrophils, causing susceptibility to pulmonary A. fumigatus infection. This study establishes a new paradigm in innate immune response in chronic ethanol consumers.

Alcoholism is a chronic disease that has many damaging effects on the body. Over long periods, excessive alcohol intake weakens the immune system, putting consumers at increased risk of getting lung infections such as pneumonia.

Some forms of pneumonia can be caused by the fungus Aspergillus fumigatus. This microbe does not tend to be a problem for healthy individuals, but it can be fatal for those with impaired immune systems. Here, Malacco et al. wanted to find out why excessive alcohol consumers are more prone to pneumonia.

To test this, the researchers used two groups of mice that were either fed plain water or water containing ethanol. After 12 weeks, both groups were infected with Aspergillus fumigatus. The results showed that alcohol-fed mice were more susceptible to the infection caused by strong inflammation of the lungs.

Normally, the immune system confronts a lung infection by activating a group of defense cells called neutrophils, which travel through the blood system to the infection site. Once in the right spot, neutrophils get to work by releasing toxins that kill the fungus. Malacco et al. discovered that after chronic alcohol consumption, neutrophils were less reactive to inflammatory signals and less likely to reach the lungs. They were also less effective in dealing with the infection. Neutrophil released fewer toxins and were thus less able to kill the microbial cells.

These findings demonstrate for the first time how alcohol can affect immune cells during infection and pave the way for new possibilities to prevent fatal lung infections in excessive alcohol consumers. A next step would be to identify how alcohol acts on other processes in the body and to find a way to modulate or even revert the changes it causes.

Immunological profile of periapical endodontic infection in patients undergoing haematopoietic transplantation

OBJECTIVES

To evaluate the mRNA expression levels of cytokines interferon-γ, tumour necrosis factor-α, interleukin IL-1β, IL-10, and the chemokine CCL2/MCP-1, CCL4, and CXCR4 in the periapical interstitial fluid from root canal infections before and after bacterial load reduction in patients undergoing haematopoietic stem cell transplantation (HSCT).

MATERIALS AND METHODS

The case group was composed of 10 patients undergoing HSCT, and our control group included 10 healthy patients. Clinical samples were taken from teeth with pulp necrosis. Three paper points were placed in the RCS and maintained for 2 min for microbial evaluation before cleaning and shaping procedures. After cleaning and drying the canal, three paper points were introduced into the root canal, passing passively through the root apex (2 mm) into the periapical tissues for 1 min. Samples were collected immediately after root canal cleaning and 7 days later (restrained root canal bacterial load) to characterize gene expression using real-time PCR.

RESULTS

The results showed significantly reduction in the microbial load on day 7. An increased expression level of TNF-α and IFN-γ on day 7 in control and case groups was observed (p < 0.05). The mRNA levels of IL-1β and IL-10 in the pre-HSCT group increased in the samples from day 7 (p < 0.05). The chemokine CCL-2/MCP-1 was not detected in pre-HSCT group. Chemokine receptor CXCR4 levels increased in samples obtained from the day 7 in the control group (p < 0.05).

CONCLUSIONS

Individuals undergoing HSTC presented similar cytokine and chemokine mRNA expression compared with healthy individuals. However, it was observed the total absence of mRNA MCP-1/CCL2 expression in those individuals undergoing HSCT.

CLINICAL RELEVANCE

Patients undergoing HSCT are at higher risk of infection. No study has analysed the periapical immune responses to root canal infections in HSCT individuals.

Role of gut microbiota in the GBR12909 model of mania-like behavior in mice

Growing evidence suggests a role for brain-gut-microbiota axis in affective disorders including major depression and bipolar disorder (BD). Herein, we aim to explore, by employing germ-free (GF) mice, the effect of the indigenous microbiota in the development of mania-like behavior. Conventional and GF mice were evaluated for the hyperlocomotion induced by the dopamine transporter inhibitor GBR12909 (15 mg/Kg), a validated model for mania-like behavior. Inflammatory mediators and neurotrophic factors were quantified in the prefrontal cortex, hippocampus and striatum. Mice lacking indigenous microbiota were less susceptible to the mania-like behavior induced by GBR12909. This effect was associated with decreased levels of inflammatory cytokines such as IL-6 and TNF-α, along with increased concentrations of anti- inflammatory cytokines (IL-10) and of neurotrophins (BDNF and NGF). We provided the first evidence that gut-microbiota-brain axis participates in the development of mania-like behavior in rodents, possibly through neuroimmunepathways.

Th1-Th2 Cross-Regulation Controls Early Leishmania Infection in the Skin by Modulating the Size of the Permissive Monocytic Host Cell Reservoir

The impact of T helper (Th) 1 versus Th2 immunity on intracellular infections is attributed to classical versus alternative activation of macrophages leading to resistance or susceptibility. However, observations in multiple infectious settings demonstrate deficiencies in mediators of Th1-Th2 immunity, which have paradoxical or no impact. We report that prior to influencing activation, Th1/Th2 immunity first controls the size of the permissive host cell reservoir. During early Leishmania infection of the skin, IFN-γ- or STAT6-mediated changes in phagocyte activation were counteracted by changes in IFN-γ-mediated recruitment of permissive CCR2⁺ monocytes. Monocytes were required for early parasite expansion and acquired an alternatively activated phenotype despite the Th1 dermal environment required for their recruitment. Surprisingly, STAT6 did not enhance intracellular parasite proliferation, but rather modulated the size and permissiveness of the monocytic host cell reservoir via regulation of IFN-γ and IL-10. These observations expand our understanding of the Th1-Th2 paradigm during infection.

Reactive oxygen species and nitric oxide imbalances lead to in vivo and in vitro arrhythmogenic phenotype in acute phase of experimental Chagas disease

Chagas Disease (CD) is one of the leading causes of heart failure and sudden death in Latin America. Treatments with antioxidants have provided promising alternatives to ameliorate CD. However, the specific roles of major reactive oxygen species (ROS) sources, including NADPH-oxidase 2 (NOX2), mitochondrial-derived ROS and nitric oxide (NO) in the progression or resolution of CD are yet to be elucidated. We used C57BL/6 (WT) and a gp91PHOX knockout mice (PHOX-/-), lacking functional NOX2, to investigate the effects of ablation of NOX2-derived ROS production on the outcome of acute chagasic cardiomyopathy. Infected PHOX-/- cardiomyocytes displayed an overall pro-arrhythmic phenotype, notably with higher arrhythmia incidence on ECG that was followed by higher number of early afterdepolarizations (EAD) and 2.5-fold increase in action potential (AP) duration alternans, compared to AP from infected WT mice. Furthermore, infected PHOX-/- cardiomyocytes display increased diastolic [Ca2+], aberrant Ca2+ transient and reduced Ca2+ transient amplitude. Cardiomyocyte contraction is reduced in infected WT and PHOX-/- mice, to a similar extent. Nevertheless, only infected PHOX-/- isolated cardiomyocytes displayed significant increase in non-triggered extra contractions (appearing in ~75% of cells). Electro-mechanical remodeling of infected PHOX-/-cardiomyocytes is associated with increase in NO and mitochondria-derived ROS production. Notably, EADs, AP duration alternans and in vivo arrhythmias were reverted by pre-incubation with nitric oxide synthase inhibitor L-NAME. Overall our data show for the first time that lack of NOX2-derived ROS promoted a pro-arrhythmic phenotype in the heart, in which the crosstalk between ROS and NO could play an important role in regulating cardiomyocyte electro-mechanical function during acute CD. Future studies designed to evaluate the potential role of NOX2-derived ROS in the chronic phase of CD could open new and more specific therapeutic strategies to treat CD and prevent deaths due to heart complications.

Obesity impairs resistance to Leishmania major infection in C57BL/6 mice

An association between increased susceptibility to infectious diseases and obesity has been described as a result of impaired immunity in obese individuals. It is not clear whether a similar linkage can be drawn between obesity and parasitic diseases. To evaluate the effect of obesity in the immune response to cutaneous Leishmania major infection, we studied the ability of C57BL/6 mice fed a hypercaloric diet (HSB) to control leishmaniasis. Mice with diet-induced obesity presented thicker lesions with higher parasite burden and a more intense inflammatory infiltrate in the infected ear after infection with L. major. There was no difference between control and obese mice in IFN-gamma or IL-4 production by auricular draining lymph node cells, but obese mice produced higher levels of IgG1 and IL-17. Peritoneal macrophages from obese mice were less efficient to kill L. major when infected in vitro than macrophages from control mice. In vitro stimulation of macrophages with IL-17 decreased their capacity to kill the parasite. Moreover, macrophages from obese mice presented higher arginase activity. To confirm the role of IL-17 in the context of obesity and infection, we studied lesion development in obese IL-17R-/- mice infected with L. major and found no difference in skin lesions and the leukocyte accumulation in the draining lymph node is redcuced in knockout mice compared between obese and lean animals. Our results indicate that diet-induced obesity impairs resistance to L. major in C57BL/6 mice and that IL-17 is involved in lesion development.

Obesity is a serious and increasing public health problem, and also induces a spectrum of metabolic disorders. Some diseases are known to be more severe in the presence of obesity. However, the interactions of obesity with the immune response to infectious agents have not been fully explored. In this study, we investigated the response of obese mice to infection with Leishmania major. C57BL/6 mice were fed a hypercaloric diet (HSB) and infected afterward with L. major. In obese mice, lesions were ticker and more ulcerative, and cells from draining lymph nodes produced more IL-17 when compared with cells from lean mice fed a control diet. Macrophages from obese and lean mice were infected in vitro and stimulated with IL-17 to test the role of this cytokine in effect produced by obesity. Macrophages from obese mice were more infected by L. major than the macrophages from control mice and the number of parasites was increased by treatment with IL-17. IL-17R deficient mice treated with hypercaloric diet showed no difference in lesion size when compared to mice fed control diet. Our findings suggest that diet-induced obesity decrease the resistance to L. major infection of C57BL/6 mice and the IL-17 cytokine may be involved in the lesion formation.

Influence of genetic regulatory effects modified by environmental immune activation on periapical disease

The objective of this study was to compare the periradicular responses in endodontic infections among members of two populations: an urban Brazilian population and a non-mixed indigenous population. Samples were collected immediately and 7 days after the cleaning and shaping procedures (after reducing the intracanal microbial load) in an attempt to characterize the expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-9, interferon (IFN)-γ, IL-17, IL-10, and the chemokines CXCR4, CCL2/monocyte chemotactic protein (MCP)-1, and CCR6. The endogenous cytokine and chemokine expression levels were analyzed using real-time PCR. Only the urban population showed a significant increase in TNF-α, CCL2/MCP-1, CXCR4, and CCR6 expression following the cleaning and shaping of the root canal system. The IFN-γ levels were increased at the 2nd collection (p < 0.05) in the indigenous population. In turn, a significant increase in IL-10 and IL-17 expression (p < 0.05) was observed after the cleaning and shaping procedures (2nd collection) in both populations. No significant differences in the IL-1β, IL-9, and CCL4 expression levels were observed between the 1st and 2nd collections in both populations. The results demonstrate a cytokine and chemokine expression profile that is specific to each analyzed population. However, immune modulation mediated by IL-10 began on the 7th day after the beginning of the endodontic treatment in both populations.

Exploring the inquiry-based learning structure to promote scientific culture in the classrooms of higher education sciences

This article examines student engagement in an inquiry-based learning activity, planned to provide students with elements in the social, epistemic, and conceptual dimensions related to the scientific practice in immunology. The activity was applied to 39 groups of students enrolled in immunology or biochemistry courses in a public university in Brazil. Students performed data-collection through the execution of an in vitro assay. We analyzed how students represent data and use them to support their claims in their written constructs. To clarify which are the productive epistemologies in students' reports, we developed a framework for epistemic practice analysis. Our findings point to a pattern of several epistemic practice categories in their written text, mostly related to the particular contingences of data analysis, rather than to theoretical concepts. In addition, we observed that students performed literary inscriptions to represent their data; however, they tended not to cite all data obtained in their written texts. These results suggest that immunology education strategies should provide students with approaches that explore the role of data representation in the scientific text rhetoric. © 2019 International Union of Biochemistry and Molecular Biology, 47(6):672-680, 2019.

Effect of ethylenediaminetetraacetic acid irrigation on immune-inflammatory response in teeth submitted to regenerative endodontic therapy

AIM

To analyse longitudinally the immune-inflammatory response in teeth of mice that underwent a regenerative protocol with or without the use of ethylenediaminetetraacetic acid (EDTA) to irrigate the root canal system.

METHODOLOGY

First maxillary molars of mice were devitalized using size 10 and 15 files. Teeth were divided into the following groups: Empty - the canals were left empty; Blood Clot (BC) - the canals were filled with a blood clot; and EDTA + Blood - the canals were irrigated with 0.06 mL of 17% EDTA for 1 min and filled with a blood clot. Access cavities were restored with Coltosol^® . Animals were sacrificed at 7, 14 or 21 days after the operative procedures, and teeth were collected. RNA was extracted, mRNA expression of the cytokines IGF, NGF, IL-1α, IL-10, TGF and VEGF was assessed using real-time PCR, and the anova Kruskal-Wallis test was used.

RESULTS

IL-1 mRNA expression was significantly higher in the EDTA + BC group than in the Empty and BC groups at the 7th and 14th days of evaluation (P < 0.05). IL-10 mRNA expression was similar across the three groups at all time periods. TGF-β mRNA expression in the EDTA + BC group was significantly higher on the 7th and 21st days than on the 14th (P < 0.05); at day 21, TGF-β mRNA expression was similar between the BC and EDTA + BC groups but significantly higher than in the Empty group (P < 0.05). IGF mRNA expression was significantly higher in the EDTA + BC group than in the other groups at all time periods. VEGF mRNA expression remained unchanged throughout the experimental period in all groups (P > 0.05). NGF mRNA expression was similar amongst all groups at the 7th and 21st days (P > 0.05). At the 14th day, however, there was a significant increase in NGF mRNA expression in the EDTA + Blood group (P < 0.05) when compared with the expression in the other groups.

CONCLUSION

EDTA promoted increased expression of factors that have the potential to improve the outcome of regenerative endodontic treatment.

Evaluation of chemokines and receptors in gnotobiotic root canal infection by F. nucleatum and E. faecalis

The present study aims to evaluate the longitudinal effects of induced experimental infections in gnotoxenic animals on the expression of inflammatory chemokines and their receptors in periradicular tissues. The null hypothesis tested was that Enterococcus faecalis and Fusobacterium nucleatum had no effect on CCR5, CCL5, CXCL10, CCL2/MCP-1, CXCR2 and CCR1 expression. Two groups of five animals (n = 5) aged between 8 and 12 weeks were used in this study. The animals were anaesthetized, and coronary access was performed in the first molar on the right and left sides. Microorganisms were inoculated into the left molar, and the right molar was sealed without contamination to function as a control. Animals were sacrificed 7 and 14 days after infection, and periapical tissues were collected. The cytokine mRNA expression levels were assessed using real-time PCR. The chemokine mRNA expression levels demonstrated that the experimental infection was capable of inducing increased chemokine expression on day 7 compared to that on day 14, except for CCR5 and CCL5, which showed no changes. The gnotoxenic animal model proved to be effective and allowed evaluation of the immune response against a known infection. Additionally, this study demonstrates that gene expression of chemokines and their receptors against the experimental infection preferentially prevailed during the initial phase of induction of the periradicular alteration (i.e., on day 7 post-infection).

Immunological profile of teeth with inflammatory periapical disease from chronic liver disease patients

AIM

To evaluate the mRNA expression levels of the cytokines interferon-γ, tumour necrosis factor-α, interleukin (IL)-1β, IL-10, IL-6, VEGF, and AGT and the chemokine CCL2/MCP-1 in periapical interstitial fluid associated with root canal infections before and after the reduction of the bacterial load using a cleaning procedure.

METHODOLOGY

The case group included 11 patients with chronic liver disease, and the control group included 11 healthy patients. Clinical samples were taken from teeth with pulp necrosis. After cleaning and drying the canal, three paper points were introduced into the root canal and passed through the root apex (2 mm) into the periapical tissues for 1 min. The samples were collected immediately after root canal cleaning and 7 days later to characterize those gene expression levels using real-time PCR. The data were subjected to the Shapiro-Wilk and the Wilcoxon tests.

RESULTS

In the control group, significantly increased expression of the pro-inflammatory cytokines IFN-γ and TNF-α was observed in teeth with restrained bacterial loads (day 7) (P < 0.05). Similarly, increased TNF-α expression was found on day 7 in the liver group (P < 0.05). No differences were observed in the expression levels of the IL-1β, IL-10 and, IL-6, MCP-1/CCL-2 and VEGF between the first collection (day 0) and second collection (day 7), over time in either group.

CONCLUSION

Chronic liver disease patients exhibited sufficient immunologic ability showing relatively similar expression levels of cytokines, chemokines and angiogenic factors in periapical samples compared with the responses from no-chronic liver disease patients. The outcomes of this study suggest that liver impairment did not compromise the periapical immune response.

Cytokine expression in response to root repair agents

AIM

To evaluate the expression of TNF-α, IL-6, IFN-γ, TGF-β, IL-4, IL-10, RANKL, RANK and OPG on mouse calvarial bone treated with MTA, Geristore^® and Emdogain^® .

METHODOLOGY

Bone wounds were made on the heads of C57BL/6 mice, breaking the periosteum and the cortical surface of the calvaria. Each repair agent was inserted into sectioned Eppendorf microtubes and placed on the bone wound, and soft tissues were sutured. At 14 and 21 days, animals were sacrificed and the treated region was dissected. The calvaria bone was removed, and RNA was extracted. mRNA expression of the aforementioned cytokines was assessed using real-time PCR. Data were analysed by nonparametric methods, including the Mann-Whitney and Kruskal-Wallis tests (P < 0.05).

RESULTS

Following treatment with Emdogain^® and MTA, mRNA expression of RANKL, RANK and OPG increased significantly (P < 0.05) between days 14 to 21. Geristore^® did not alter the basal expression of these mediators during the same period of evaluation. Whilst treatment with Emdogain^® did cause a significant increase in TNF-α mRNA expression between days 14 and 21 (P < 0.05), treatment with MTA did not alter the basal expression of this cytokine at either experimental time point. However, TNF-α mRNA expression was down-regulated significantly at day 21 (P < 0.05) when Geristore^® was applied. A significant increase in the mRNA expression of IL-6, TGF-β, IL-10, IL-4 and IFN-γ was observed with Emdogain^® and MTA treatment between days 14 to 21, whereas Geristore^® reduced significantly the expression of IL-6, TGF-β and IL-4 (P < 0.05).

CONCLUSION

The clinical indication of these repair agents depends on the root resorption diagnosis. Whilst MTA and Emdogain^® induce a pro- and anti-inflammatory response early and late, respectively, Geristore^® was not associated with an inflammatory reaction when compared with both repair agents.

Epidemiological analysis and need for endodontic treatment among the indigenous Sateré-Mawé and Tikuna

The objective of this study was to analyze the epidemiological profile of oral health of Sateré-Mawé indigenous people living in Barreirinha, Amazonas (AM), Brazil, and the Tikuna indigenous people living in the urban area of Manaus (AM), in addition to characterizing the need for endodontic treatment between the two ethnic groups. A total of 138 individuals participated in the study, of whom 98 were Tikuna and 40 were Sateré-Mawé; they were distributed in age groups ranging from seven to 75 years. A very high prevalence of caries was observed in both ethnic groups. For the Sateré-Mawé in the 7-12 age group, the decayed, missing, and filled teeth (DMFT) index presented a mean value of 3.17. Comparing the DMFT index and the need for endodontic treatment in each of the ethnicities, these variables were found to be correlated, because as the DMFT index increases, the chances of needing endodontic treatment increase. The Sateré-Mawé presented a higher prevalence of need for endodontic treatment compared to the Tikuna. The association of comorbidities and the need for endodontic treatment were demonstrated only in the Tikuna, and there was only a correlation of this necessity with the presence of diabetes mellitus (DM) in one case. The need to expand access to oral health in these communities is emphasized, taking into account geographical access and technological, environmental, linguistic, and cultural barriers.

The need for endodontic treatment and systemic characteristics of hematopoietic stem cell transplantation patients

The aim of this study is to investigate the relationship between the epidemiological and clinical profiles of patients before and after hematopoietic stem cell transplantation (HSCT) and the need for endodontic treatment. The subjects included 188 individuals enrolled in the dental care program for transplanted patients of the School of Dentistry, Federal University of Minas Gerais (Faculdade de Odontologia da Universidade Federal de Minas Gerais, FO-UFMG) from March 2011 through March 2016. The patients were subjected to an HSCT conditioning dental regimen based on a thorough clinical and radiographic evaluation. Intraoral periapical and bite-wing X-rays were obtained, and after evaluation, specific dental treatment was planned and performed. The following demographic and clinical data were collected from the patients' medical records: age, gender, transplantation stage, primary disease, transplant type, medication used, complete blood count at the time of visit, and need for endodontic treatment. The Kolmogorov-Smirnov and the chi-square tests were used. Leukemia (31.3%) and multiple myeloma (17.9%) were the most prevalent primary diseases. Most patients were subjected to allogeneic-related transplantation (83.6%). Most patients exhibited platelet counts and hemoglobin concentrations below the reference values in the pre-transplantation stage, while the neutrophil and platelet counts and the hemoglobin levels were within the reference ranges in the post-transplantation stage. The proportions of individuals requiring endodontic treatment were similar between the pre- and post-transplantation groups: 24.3% and 24.7%, respectively. The systemic conditions of the patients referred for dental treatment were compromised.

TNF and IL-18 cytokines may regulate liver fat storage under homeostasis conditions

The inflammation induced by obesogenic diets is associated with deposition of fat in the liver. On the other hand, anti-inflammatory and immunosuppressive therapies may impact in body fat storage and in liver lipid dynamics. It is important to study specific inflammatory mediators in this context, since their role on hepatic damage is not fully clarified. This study aimed to evaluate the role of interleukin (IL)-18 and tumor necrosis factor (TNF) receptor in liver dysfunction induced by diet. Male C57BL/6 wild-type (WT), IL-18, and TNF receptor 1 knockout mice (IL-18^-/- and TNFR1^-/-) were divided according to the experimental diets: chow diet or a high-refined carbohydrate-containing diet. Alanine aminotransferase was quantified by colorimetric analysis. Total fat content in the liver was determined by Folch methods. Levels of TNF, IL-6, IL-4, and IL-13 in liver samples were measured by ELISA assay. IL-18 and TNFR knockout mice fed with chow diet showed higher liver triglycerides deposition than WT mice fed with the same diet (WT: 131.9 ± 24.5; IL-18^-/-: 239.4 ± 38.12*; TNF^-/-: 179.6 ± 50.45*; *P < 0.01). Furthermore, these animals also showed a worse liver histopathological score and lower levels of TNF, IL-6, IL-4, and IL-13 in the liver. Interestingly, treatment with a high-carbohydrate diet did not exacerbate liver damage in IL-18^-/- and TNFR1^-/- mice. Our data suggest that IL-18 and TNF may be involved on hepatic homeostasis mainly in a context of a healthy diet.

IFN-γ-Dependent Recruitment of CD4(+) T Cells and Macrophages Contributes to Pathogenesis During Leishmania amazonensis Infection

Interferon gamma (IFN-γ) is a key factor in the protection of hosts against intracellular parasites. This cytokine induces parasite killing through nitric oxide and reactive oxygen species production by phagocytes. Surprisingly, during Leishmania amazonensis infection, IFN-γ plays controversial roles. During in vitro infections, IFN-γ induces the proliferation of the amastigote forms of L. amazonensis. However, this cytokine is not essential at the beginning of an in vivo infection. It is not clear why IFN-γ does not mediate protection during the early stages of infection. Thus, the aim of our study was to investigate the role of IFN-γ during L. amazonensis infection. We infected IFN-γ(-/-) mice in the footpad and followed the development of leishmaniasis in these mice compared with that in WT mice. CD4(+) T lymphocytes and macrophages migrated earlier to the site of infection in the WT mice, and the earlier migration of these 2 cell types was associated with lesion development and parasite growth, respectively. These differences in the infiltrate populations were explained by the increased expression of chemokines in the lesions of the WT mice. Thus, we propose that IFN-γ plays a dual role during L. amazonensis infection; it is an important inducer of effector mechanisms, particularly through inducible nitric oxide synthase expression, and conversely, it is a mediator of inflammation and pathogenesis through the induction of the expression of chemokines. Our data provided evidence for a pathogenic effect of IFN-γ production during leishmaniasis that was previously unknown.

Experimental Furcal Perforation Treated with MTA: Analysis of the Cytokine Expression

<p>The aim of this study was to evaluate mineral trioxide aggregate (MTA)-induced cytokine expression in mice after experimental furcal perforation. BALB/c mice (n=5) were subjected to induced furcal drilling of the maxillary first molar followed by MTA sealing in the left side (experimental group) and paraffin sealing in the right side (control group). Animals were euthanized at 7, 14 and 21 days after sealing the perforations. The expression levels of the IFN-γ, TNF-α, IL-10, IL-4, TGF-β and RANKL genes were investigated by real time polymerase chain reaction (PCR) in the teeth and surrounding tissues. In the experimental groups, after the 7th day, there was a down-regulation of the mRNA levels of TNF-α and IL-4 compared to the 14th day (p<0.05). In these groups, the mRNA levels of RANKL, IFN-γ and TNF-α were statistically higher after 14 days compared to 21 days post-MTA sealing (p<0.05). The level of IL-10 mRNA was increased at the 21st day (p<0.05). The mRNA expression of TGF-β did not exhibit any statistically relevant results. There was a statistical down-regulation of IL-4 gene expressions when control and experimental groups were compared at days 7 and 21. In conclusion, MTA sealing favored the expression of pro-inflammatory cytokines in the intermediate phase of the immuno-inflammatory response (14th day). The reduction of these cytokines in later phase of the response was probably due to immunoregulation by IL-10.</p>

Assessment of the cytotoxicity of a mineral trioxide aggregate-based sealer with respect to macrophage activity

AIM

To assess the influence of co-culture with mineral trioxide aggregate (MTA) and MTA Fillapex (FLPX) on the viability, adherence, and phagocytosis activity of peritoneal macrophages from two mouse strains.

METHODOLOGY

Cellular viability, adherence, and phagocytosis of Saccharomyces boulardii were assayed in the presence of capillaries containing MTA and MTA Fillapex. The data were analyzed using parametric (Student's t) and non-parametric (Mann-Whitney) tests.

RESULTS

FLPX was severely cytotoxic and decreased cell viability, adherence, and phagocytic activity of both macrophage subtypes. Cells that were treated with MTA Fillapex remained viable (>80%) for only 4 h after stimulation. Macrophages from C57BL/6 mice presented higher adherence and higher phagocytic activity compared with macrophages from BALB/c mice.

CONCLUSION

Comparison of MTA and FLPX effects upon macrophages indicates that FLPX may impair macrophage activity and viability, while MTA seems to increase phagocytic activity.

Immunological profile of periapical endodontic infections from HIV- and HIV+ patients

AIM

To evaluate CD4(+) CD28(+) and CD8(+) T-cell genes and the gene expression of IFN-γ, TNF-α, IL-1-β, IL-17A, IL-10, CCL-2/MCP-1, CCL-4, CCL-5 (RANTES), CXCR4, CCR5 and RANKL from cells in the periapical interstitial fluid from root canal infections in healthy patients (HIV-) and HIV-positive individuals (HIV+).

METHODOLOGY

Subjects included 20 HIV- and 23 HIV+ patients referred to the School of Dentistry at the Universidade Federal de Minas Gerais (Belo Horizonte, MG, Brazil). Almost all HIV+ patients were undergoing highly active antiretroviral therapy (HAART). Clinical samples were taken from teeth with pulp necrosis, and no patients had acute periapical symptoms at the time of the appointments. After cleaning and drying, 3 paper points were introduced into the root canal, passing passively through the root apex (2 mm) into the periapical tissues for 1 min. The samples were collected immediately after root canal cleaning and 7 days later (restrained root canal bacterial load) to characterize those gene expressions using real-time PCR.

RESULTS

Significantly higher levels of CD4(+) CD28(+) and CD8(+) T cells in teeth with restrained bacterial loads (second collection) compared with the first collection were observed in both HIV- and HIV+ samples. In HIV- patients, an increase in IL-10 and CXCR4 expression was demonstrated as well as a decrease in pro-inflammatory cytokines such as RANKL, IFN-γ, IL1-β and CCL5. However, in HIV+ patients an increase in cytokines IFN-γ, IL-1-β, TNF-α and IL-17A, and chemokines CCL-2, CXCR4 and CCR5 were observed. The chemokine CCL-5 was not detected in HIV+ individuals.

CONCLUSIONS

These findings suggest that after reducing the root canal bacterial load in HIV- individuals an anti-inflammatory response is generated whilst in HIV+ patients a pro-inflammatory response is sustained in the periapical area.

Arginine Supplementation Induces Arginase Activity and Inhibits TNF-α Synthesis in Mice Spleen Macrophages After Intestinal Obstruction

BACKGROUND

The purpose of this study was to assess the effect of arginine supplementation on arginase activity, tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) synthesis in cultured splenic macrophages from a murine model of intestinal obstruction (IO). The effects of nitric oxide synthase (iNOS) inhibition were also studied using iNOS knockout animals.

MATERIAL AND METHODS

Male C57BL6/J wild-type (WT) and iNOS knockout (iNOS-/-) mice were randomized into 6 groups: Sham and Sham-/- (standard chow), IO and IO-/- (standard chow + IO), and Arg and Arg-/- (standard chow supplemented with arginine + IO). After 7 days of treatment with standard or supplemented chow, IO was induced. Arginase activity as well as TNF-α and IL-10 levels were analyzed in splenic macrophage cultures.

RESULTS

Arginine supplementation and the absence of iNOS increased arginase activity in splenic macrophages (Arg, IO-/-, and Arg-/- groups vs the Sham group; P < .05). Arginine was also related to a decrease in TNF-α levels (Arg vs IO group, P < .05) and maintenance of IL-10 levels (Arg vs other groups, P > .05). The inhibition of iNOS did not result in effects on the concentration of cytokines (Sham-/-, IO-/-, and Arg-/- vs other, P < .05).

CONCLUSIONS

Arginine supplementation and iNOS inhibition led to increased arginase activity. Arginine availability decreased plasma TNF-α levels, which may be directly related to nitric oxide derived from arginine.

Short-term protection conferred by Leishvacin® against experimental Leishmania amazonensis infection in C57BL/6 mice

To date, there is no vaccine available against human leishmaniasis. Although some vaccination protocols can induce immunity in murine models, they fail to induce protection in humans. The reasons for that remain unclear. The aim of the present study was to characterize the changes in the pattern of the immune response during subcutaneous vaccination with Leishvacin® in mice. We also investigated whether IFN-γ and nitric oxide synthase are indispensable for the protection elicited by the vaccine. C57BL/6 WT vaccinated mice showed smaller lesions and fewer numbers of parasites in footpads until 8 weeks post-infection. Up to this time, they produced higher levels of IFN-γ, IL-2, IL-4, IL-17A and IL-10 and higher specific antibody response than control non-vaccinated mice. Moreover, we showed that IFN-γ, most likely by induction of iNOS expression, is essential for immunity. However, after 12 weeks of infection, we observed loss of difference in lesion size and parasite burden between the groups. Loss of resistance was associated with the disappearance of differences in cytokine patterns between vaccinated and control mice, but not of antibody response, which remained different until a later time of infection. The reversal of resistance to L. amazonensis could not be explained by upregulation of regulatory cytokines. Our data point to a subversion of the host immune response by L. amazonensis even when a protective response was previously induced.

Leishmania braziliensis amastigotes stimulate production of IL-1β, IL-6, IL-10 and TGF-β by peripheral blood mononuclear cells from nonendemic area healthy residents

Leishmania (Viannia) braziliensis causes cutaneous and mucosal leishmaniasis in several countries in Latin America. In mammals, the parasites live as amastigotes, interacting with host immune cells and stimulating cytokine production that will drive the type of the specific immune responses. Generation of Th17 lymphocytes is associated with tissue destruction and depends on IL-1β, IL-6, TGF-β and IL-23 production, whereas IL-10 and TGF-β are associated with tissue protection. Here, we evaluate whether amastigotes stimulate peripheral blood mononuclear cells (PBMCs) from healthy donors to produce the major cytokines responsible for the generation of Th17. Seven L. (V.) braziliensis isolates from patients with different clinical forms of leishmaniasis were expanded in interferon-γ knockout mice to obtain amastigotes and in culture to get promastigotes. The parasites were used to stimulate PBMCs from healthy donors, and cytokine production was evaluated by ELISA or qPCR. Amastigotes and promastigotes induced IL-10 production in PBMCs; however, only amastigotes induced IL-1β, IL-6 and TGF-β. These data demonstrate for the first time that L. (V.) braziliensis amastigotes directly stimulate production of a unique pattern of cytokines that could contribute to the generation of Th17.

Interleukin 32γ (IL-32γ) is highly expressed in cutaneous and mucosal lesions of American Tegumentary Leishmaniasis patients: association with tumor necrosis factor (TNF) and IL-10

Background

The interleukin 32 (IL-32) is a proinflammatory cytokine produced by immune and non-immune cells. It can be induced during bacterial and viral infections, but its production was never investigated in protozoan infections. American Tegumentary Leishmaniasis (ATL) is caused by Leishmania protozoan leading to cutaneous, nasal or oral lesions. The aim of this study was to evaluate the expression of IL-32 in cutaneous and mucosal lesions as well as in peripheral blood mononuclear cells (PBMC) exposed to Leishmania (Viannia) braziliensis.

Methods

IL-32, tumour necrosis factor (TNF) and IL-10 protein expression was evaluated by immunohistochemistry in cutaneous, mucosal lesions and compared to healthy specimens. The isoforms of IL-32α, β, δ, γ mRNA, TNF mRNA and IL-10 mRNA were assessed by qPCR in tissue biopsies of lesions and healthy skin and mucosa. In addition, PBMC from healthy donors were cultured with amastigotes of L. (V.) braziliensis. In lesions, the parasite subgenus was identified by PCR-RFLP.

Results

We showed that the mRNA expression of IL-32, in particular IL-32γ was similarly up-regulated in lesions of cutaneous (CL) or mucosal (ML) leishmaniasis patients. IL-32 protein was produced by epithelial, endothelial, mononuclear cells and giant cells. The IL-32 protein expression was associated with TNF in ML but not in CL. IL-32 was not associated with IL-10 in both CL and ML. Expression of TNF mRNA was higher in ML than in CL lesions, however levels of IL-10 mRNA were similar in both clinical forms. In all lesions in which the parasite was detected, L. (Viannia) subgenus was identified. Interestingly, L. (V.) braziliensis induced only IL-32γ mRNA expression in PBMC from healthy individuals.

Conclusions

These data suggest that IL-32 plays a major role in the inflammatory process caused by L. (Viannia) sp or that IL-32 is crucial for controlling the L. (Viannia) sp infection.

Regulatory effects of IL-18 on cytokine profiles and development of myocarditis during Trypanosoma cruzi infection

Chagas disease, caused by Trypanosoma cruzi (Tc), is an important cause of heart disease. Resistance to Tc infection is multifactorial and associated with Th1 response. IL-18 plays an important role in regulation of IFN-γ production/development of Th1 response. However, the role of IL-18 in the setting of Tc infection remains unclear. Therefore, we investigated the role of IL-18 in the modulation of immune response and myocarditis in Tc infection. C57BL/6 and IL-18 KO mice were infected with Tc (Y or Colombian strain) and parasitemia, immune response and pathology were evaluated. Y strain infection of IL-18 KO did not alter any parameters when compared with C57BL/6 mice. However, during the acute phase (20 and 40 days post infection-dpi), Colombian strain infected-IL-18 KO mice displayed higher serum levels of IL-12 and IFN-γ, respectively, and at the chronic phase (100 dpi) an increase in splenic IFN-γ-producing CD4(+) and CD8(+) T memory cells. There was an IL-10, FOXP3 and CD4(+)CD25(+) cells reduction during acute infection in spleen. Additionally, there was a significant reduction in leukocyte infiltration and parasite load in myocardium of chronically infected IL-18 KO mice. Collectively, these data indicate that IL-18 contributes to the pathogenesis of Tc-induced myocarditis when infected with Colombian but not Y strain. These observations also underscore that parasite and host strain differences are important in evaluation of experimental Tc infection pathogenesis.

Neutrophils have a protective role during early stages of Leishmania amazonensis infection in BALB/c mice

Neutrophils are involved in the early stages of immune responses to pathogens. Here, we investigated the role of neutrophils during the establishment of Leishmania amazonensis infection in BALB/c and C57BL/6 mice. First, we showed an accumulation of neutrophils between 6 and 24 h post-infection, followed by a reduction in neutrophil numbers after 72 h. Next, we depleted neutrophils prior to infection using RB6-8C5 or 1A8 mAb. Neutrophil depletion led to faster lesion development, increased parasite numbers and higher arginase activity during the first week of infection in BALB/c mice, but not in C57BL/6 mice. Increased susceptibility was accompanied by augmented levels of anti-L. amazonensis IgG and increased production of IL-10 and IL-17. Because IL-10 is a mediator of susceptibility to Leishmania infection, we blocked IL-10 signalling in neutrophil-depleted mice using anti-IL-10R. Interestingly, inhibition of IL-10 signalling abrogated the increase in parasite loads observed in neutrophil-depleted mice, suggesting that parasite proliferation is at least partially mediated by IL-10. Additionally, we tested the effect of IL-17 in inflammatory macrophages and observed that IL-17 increased arginase activity and favoured parasite growth. Taken together, our data indicate that neutrophils control parasite numbers and limit lesion development during the first week of infection in BALB/c mice.

Interleukin-4 deficiency protects mice from acetaminophen-induced liver injury and inflammation by prevention of glutathione depletion

OBJECTIVE

Interleukin-4 (IL-4) is a multifunctional cytokine involved in many diseases such as autoimmune hepatitis and idiosyncratic drug reactions. However, its role in acetaminophen (APAP)-induced liver injury remains unclear. Our objective was to evaluate the contribution of IL-4 to the pathogenesis of APAP-induced liver injury.

METHODS

Balb/C (WT) and IL-4 knockout (IL-4(-/-)) mice were orally overdosed with APAP. After 24 h, survival percentage, biochemical and morphological markers of liver injury, and tissue inflammation were assessed.

RESULTS

IL-4(-/-) mice were protected from APAP toxicity. Intravital confocal microscopy, tissue histology and serum ALT levels showed significantly less liver injury and inflammation than in the WT group, which may explain the increased survival rate of IL-4(-/-) mice. In addition, IL-4(-/-) mice had decreased production of tumor necrosis factor α, CXCL1 and interleukin-1β in the liver, but not in a remote site such as the lungs. Hepatic macrophage activation was markedly reduced in IL-4-deficient mice. In addition, glutathione depletion-a primary cause of APAP-mediated injury-was significantly attenuated in IL-4(-/-) mice.

CONCLUSIONS

Taken together, our data demonstrate that IL-4(-/-) mice are protected from APAP-induced liver injury due to reduced depletion of glutathione, which prevented liver damage and tissue inflammation.

In vitro and in vivo evaluation of the biocompatibility of a calcium phosphate/poly(lactic-co-glycolic acid) composite

This study assess the effects of bioceramic and poly(lactic-co-glycolic acid) composite (BCP/PLGA) on the viability of cultured macrophages and human dental pulp fibroblasts, and we sought to elucidate the temporal profile of the reaction of pulp capping with a composite of bioceramic of calcium phosphate and biodegradable polymer in the progression of delayed dentine bridge after (30 and 60 days) in vivo. Histological evaluation of inflammatory infiltrate and dentin bridge formation were performed after 30 and 60 days. There was similar progressive fibroblast growth in all groups and the macrophages showed viability. The in vivo study showed that of the three experimental groups: BCP/PLGA composite, BCP and calcium hydroxide (Ca(OH)(2)) dentin bridging was the most prevalent (90 %) in the BCP/PLGA composite after 30 days, mild to moderate inflammatory response was present throughout the pulp after 30 days. After 60 days was observed dentine bridging in 60 % and necrosis in 40 %, in both groups. The results indicate that understanding BCP/PLGA composite is biocompatible and by the best tissue response as compared to calcium hydroxide in direct pulp capping may be important in the mechanism of delayed dentine bridge after 30 and 60 days.

Microbiologic profile of endodontic infections from HIV- and HIV+ patients using multiple-displacement amplification and checkerboard DNA-DNA hybridization

OBJECTIVE

To compare the microbiota of endodontic infections in necrotic pulp from HIV-negative and HIV-positive subjects.

MATERIALS AND METHODS

Root canal samples from necrotic pulp were collected from 40 HIV- and 20 HIV+ subjects. Pulps were amplified using multiple displacement amplification (MDA). Then, checkerboard DNA-DNA hybridization was employed to assess the levels of 107 microbial taxa. The percentage of DNA probe count and the percentage of teeth colonized by each test species were investigated. Significant differences between groups regarding proportions of taxa and prevalence of the test species were sought using the Mann-Whitney test and the Chi-square analysis, respectively.

RESULTS

The most prevalent taxa detected were Dialister pneumosintes, Stenotrophomonas maltophilia, Streptococcus sobrinus, Corynebacterium diphteriae, and Helicobacter pylori among HIV- subjects and D. pneumosintes, Prevotella tannerae, Porphyromonas gingivalis, Parvimonas micra, Prevotella nigrescens, and Corynebacterium diphtheriae among HIV+ individuals. D. pneumosintes, C. diphtheria, and C. albicans were the most abundant species in the HIV- group, whereas the predominant taxa in HIV+ samples were P. tannerae, D. pneumosintes and Olsenella uli. P. tannerae, O. uli, Veilonella dispar, Bacteroides fragilis, and Actinomyces meyeri were significantly more abundant in HIV+ samples.

CONCLUSIONS

There were significant differences in the prevalence and proportions of specific microbial taxa between HIV- and HIV+ individuals. The root canal microbiota may represent a reservoir of important oral and medical pathogens, mainly in HIV+ individuals.

The role of iNOS and PHOX in periapical bone resorption

Nitric oxide (NO) and reactive oxygen species (ROS) are key molecules in resistance to pathogens. Little is known about their role in pathogenesis of periapical lesions. To address this issue, we induced periapical lesions in mice lacking nitric oxide synthase (iNOS(-/-)) or phagocyte oxidase (PHOX(-/-)). iNOS(-/-) mice expressed higher levels of IL-1β, TNF-α, RANK, RANKL, and MCP-1 than C57BL/6 and PHOX(-/-). Apical thickening of the periodontal ligament was also greater in iNOS(-/-) compared with other groups. Interestingly, ROS production did not interfere in periapical lesion progression, but seemed to be essential for the appearance of multinucleated TRAP-positive cells. Thus, periapical lesion progression in iNOS(-/-) was associated with an imbalance of pro-inflammatory cytokines (IL-1β and TNF-α), bone-resorptive modulators (RANK and RANKL), and MCP-1. We conclude that NO, but not ROS, controls progression of bone resorption in a murine experimental model of apical periodontitis.

Lactobacillus delbrueckii UFV-H2b20 induces type 1 cytokine production by mouse cells in vitro and in vivo

Lactobacillus delbrueckii UFV-H2b20 has been shown to increase clearance of bacteria injected into the blood of germ-free mice. Moreover, it induces the production of type 1 cytokines by human peripheral mononuclear cells. The objective of the present study was to investigate the production of inflammatory cytokines [interleukin-12 (IL-12 p40), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma)] triggered in vitro by live, heat-killed or lysozyme-treated L. delbrueckii UFV-H2b20 and in vivo by a live preparation. Germ-free, L. delbrueckii-monoassociated and lipopolysaccharide (LPS)-resistant C3H/HeJ mice were used as experimental models. UFV-H2b20 induced the production of IL-12 p40 and TNF-alpha by peritoneal cells and IFN-gamma by spleen cells from germ-free or monoassociated Swiss/NIH mice and LPS-hyporesponsive mice (around 40 ng/mL for IL-12 p40, 200 pg/mL for TNF-alpha and 10 ng/mL for IFN-gamma). Heat treatment of L. delbrueckii did not affect the production of these cytokines. Lysozyme treatment decreased IL-12 p40 production by peritoneal cells from C3H/HeJ mice, but did not affect TNF-alpha production by these cells or IFN-gamma production by spleen cells from the same mouse strain. TNF-alpha production by peritoneal cells from Swiss/NIH L. delbrueckii-monoassociated mice was inhibited by lysozyme treatment. When testing IL-12 p40 and IFN-gamma levels in sera from germ-free or monoassociated Swiss/NIH mice systemically challenged with Escherichia coli we observed that IL-12 p40 was produced at marginally higher levels by monoassociated mice than by germ-free mice (40 vs 60 ng/mL), but IFN-gamma was produced earlier and at higher levels by monoassociated mice (monoassociated 4 and 14 ng/mL 4 and 8 h after infection, germfree 0 and 7.5 ng/mL at the same times). These results show that L. delbrueckii UFV-H2b20 stimulates the production of type 1 cytokines in vitro and in vivo, therefore suggesting that L. delbrueckii might have adjuvant properties in infection in which these cytokines play a major role.

Mast cell degranulation contributes to susceptibility to Leishmania major

Leishmaniasis causes high morbidity and mortality in tropical and subtropical areas. Mast cells can be activated by Leishmania or Leishmania products in vitro and in vivo. Several innate immunity mediators, including some released by mast cells, play roles in the outcome of the disease. In this study, we examined whether pharmacological inactivation of mast cells before infection with L. major interferes with the progressive disease in BALB/c mice. The results show that, when mast cells are degranulated before challenge with L. major, susceptible mice become more resistant to infection, as measured by decrease of lesion size and lower parasite loads. Mast cell degranulation reduced IL-4 production. Moreover, mast cells degranulation enhanced mRNA expression for IFN-gamma, inducible nitric oxide, CCL2 and CCL5 in response to infection. Mast cell degranulation also decreased parasite loads in IL-4 KO animals, indicating that mediators other than IL-4 are involved in susceptibility in vivo. Taken together, our results disclose a role for mast cells in the induction of susceptibility to infection. This work contributes to a better understanding of the role of mast cells in Leishmania infection, and suggests a new field of study for strategies to contain the parasite, restricting its dissemination.

The influence of mineral trioxide aggregate on adaptive immune responses to endodontic pathogens in mice

This study assessed the influence of mineral trioxide aggregate (MTA) on adaptive immune responses. BALB/c mice were immunized with heat-killed Fusobacterium nucleatum (Fn) in MTA or other control adjuvants, and serum IgG responses to Fn were measured. Either Fn- or Peptostreptococcus anaerobius (Pa)-reactive memory T cells (Tm) were preincubated in vitro with/without MTA and restimulated with Fn or Pa. Tm proliferation and cytokine production were assessed. Compared with control groups, immunoglobulin G-antibody responses were upregulated in mice immunized with Fn in MTA in a similar manner to animals immunized with Fn in Freund's adjuvant or aluminum hydroxide adjuvant. Although MTA did not affect the upregulated expression of interleukin 10, tumor necrosis factor alpha, or RANKL by Tm, it suppressed the proliferation of Pa- or Fn-Tm and inhibited their production of Th1- or Th2-signature cytokines. MTA upregulated the adaptive humoral immune responses but had little or no effect on pro- or anti-inflammatory cytokine production by Tm.

Chronic antigen ingestion protects ovalbumin sensitized mice from severe manifestation of Leishmania major infection

In the present work, the development of experimental leishmaniasis was examined in sensitized BALB/c mice that were chronically fed with antigen. After an oral challenge with egg white solution, the ovalbumin (Ova)-sensitized mice showed an increase in serum anti-Ova IgE and IgG1 antibodies. Lesions induced by Leishmania major infection were reduced by the ingestion of Ova in sensitized mice, as assessed by reduced footpad growth, lower parasite loads and improved pathological outcome compared to sham sensitized mice. Moreover, such findings were connected to a shift to a Th1 response involving higher IFN-gamma production and serum levels of IgG2a anti-Leishmania antigens. The data appear to corroborate the suggestion that chronic ingestion of an antigen by sensitized mice modulates the immunological system through a shift in cytokine release, exhibiting a healing response and resistance to L. major infection.

The role of Toll-like receptors 2 and 4 on reactive oxygen species and nitric oxide production by macrophage cells stimulated with root canal pathogens

INTRODUCTION

Periapical lesions arise as a result of the activation and interaction of the host immune responses against root canal infection. Recently identified Toll-like receptors (TLR) seem to be involved in the recognition and development of immune responses against a myriad of microorganisms. However, very little information is available on the role of TLR in the induction of periapical lesions.

METHOD

The role of TLR-2 and TLR-4 in the activation of murine macrophages stimulated using Fusobacterium nucleatum and Peptostreptococcus anaerobius was investigated. The production of nitric oxide (NO) and reactive oxygen species (ROS) was assessed.

RESULTS

The results demonstrate that TLR-2 and TLR-4 are involved in the production of ROS by activated macrophages. The microorganisms induced similar levels of NO production by TLR-2-competent and TLR-2-deficient macrophages, regardless of the addition of interferon-gamma (IFN-gamma), ruling out a role for TLR-2 in the NO production induced by these bacteria. Only P. anaerobius induced NO production by TLR-4-competent macrophages without the addition of IFN-gamma. However, after IFN-gamma addition, F. nucleatum induced macrophage NO production. Therefore, NO production stimulated by IFN-gamma and these microorganisms seems to be TLR-4-independent.

CONCLUSION

TLR-2 seems to be involved in the induction of ROS production by macrophages in response to prevalent root canal bacteria, while only F. nucleatum induced ROS production by TLR-4-competent macrophages. Both microorganisms significantly induced large amounts of NO independent of TLR-2 and TLR-4. We conclude that microorganisms may participate in the induction and progression of periapical lesions through NO and ROS production by activated macrophages.

The effect of mineral trioxide aggregate on phagocytic activity and production of reactive oxygen, nitrogen species and arginase activity by M1 and M2 macrophages

AIM

To assess the influence of co-culture with mineral trioxide aggregate (MTA) on phagocytosis and the production of reactive oxygen intermediates (ROI) and nitrogen (NO) species and the arginase activity by M1 and M2 peritoneal macrophages.

METHODOLOGY

Cellular viability, adherence and phagocytosis of Saccharomyces boulardii were assayed in the presence of MTA. Macrophages were stimulated with zymosan for ROI assays and with Fusobacterium nucleatum and Peptostreptococcus anaerobius and IFN-gamma for NO production and arginase activity, when in contact with capillaries containing MTA. Data were analysed by T, anova, Kruskall-Wallis and Mann-Whitney tests.

RESULTS

M2 macrophages displayed greater cellular viability in polypropylene tubes, greater ability to ingest yeast and smaller production of ROI and higher arginase activity when compared with M1 macrophages. Both macrophages, M1 and M2, presented similar cell adherence and NO production. The addition of bacterial preparations to macrophages interfered with NO and arginase productions. MTA did not interfere with any of the parameters measured.

CONCLUSIONS

Phagocytosis and the ability of the two macrophage subtypes to eliminate microbes were not affected by MTA.