New Insights into Immunopathology Associated to Bothrops lanceolatus Snake Envenomation: Focus on PLA2 Toxin.

The systemic increase in inflammatory mediator levels can induce diverse pathological disorders, including potentially thrombus formation, which may be lethal. Among the clinical conditions in which the formation of thrombi dictates the patient's prognosis, envenomation by Bothrops lanceolatus should be emphasized, as it can evolve to stroke, myocardial infarction and pulmonary embolism. Despite their life-threatening potential, the immunopathological events and toxins involved in these reactions remain poorly explored. Therefore, in the present study, we examined the immunopathological events triggered by a PLA2 purified from B. lanceolatus venom, using an ex vivo human blood model of inflammation. Our results showed that the purified PLA2 from the venom of B. lanceolatus damages human erythrocytes in a dose dependent way. The cell injury was associated with a decrease in the levels of CD55 and CD59 complement regulators on the cell surface. Moreover, the generation of anaphylatoxins (C3a and C5a) and the soluble terminal complement complex (sTCC) indicates that human blood exposure to the toxin activates the complement system. Increased production of TNF-α, CXCL8, CCL2 and CCL5 followed complement activation. The venom PLA2 also triggered the generation of lipid mediators, as evidenced by the detected high levels of LTB4, PGE2 and TXB2. The scenario here observed of red blood cell damage, dysfunctions of the complement regulatory proteins, accompanied by an inflammatory mediator storm, suggests that B. lanceolatus venom PLA2 contributes to the thrombotic disorders present in the envenomed individuals.

Complement System Inhibition Modulates the Inflammation Induced by the Venom of Premolis semirufa, an Amazon Rainforest Moth Caterpillar.

The caterpillar of the Premolis semirufa moth, commonly called Pararama, is found in the Brazilian Amazon region. Contact with the hairs can cause a chronic inflammatory reaction, termed "pararamosis". To date, there is still no specific treatment for pararamosis. In this study, we used a whole human blood model to evaluate the involvement of the complement in the proinflammatory effects of P. semirufa hair extract, as well as the anti-inflammatory potential of complement inhibitors in this process. After treatment of blood samples with the P. semirufa hair extract, there was a significant increase in the generation of soluble terminal complement complex (sTCC) and anaphylatoxins (C3a, C4a, and C5a), as well as the production of the cytokines TNF-α and IL-17 and the chemokines IL-8, RANTES, MIG, MCP-1, and IP-10. The inhibition of C3 with compstatin significantly decreased IL-17, IL-8, RANTES, and MCP-1 production. However, the use of the C5aR1 antagonist PMX205 promoted a reduction in the production of IL-8 and RANTES. Moreover, compstatin decreased CD11b, C5aR1, and TLR2 expression induced by P. semirufa hair extract in granulocytes and CD11b, TLR4, and TLR2 in monocytes. When we incubated vascular endothelial cells with extract-treated human plasma, there was an increase in IL-8 and MCP-1 production, and compstatin was able to decrease the production of these chemokines. C5aR1 antagonism also decreased the production of MCP-1 in endothelial cells. Thus, these results indicate that the extract of the Pararama bristles activates the complement system and that this action contributes to the production of cytokines and chemokines, modulation of the expression of surface markers in leukocytes, and activation of endothelial cells.

Bothrops jararaca Snake Venom Inflammation Induced in Human Whole Blood: Role of the Complement System.

The clinical manifestations of envenomation by Bothrops species are complex and characterized by prominent local effects that can progress to tissue loss, physical disability, or amputation. Systemic signs can also occur, such as hemorrhage, coagulopathy, shock, and acute kidney failure. The rapid development of local clinical manifestations is accompanied by the presence of mediators of the inflammatory process originating from tissues damaged by the bothropic venom. Considering the important role that the complement system plays in the inflammatory response, in this study, we analyzed the action of Bothrops jararaca snake venom on the complement system and cell surface receptors involved in innate immunity using an ex vivo human whole blood model. B. jararaca venom was able to induce activation of the complement system in the human whole blood model and promoted a significant increase in the production of anaphylatoxins C3a/C3a-desArg, C4a/C4a-desArg, C5a/C5a-desArg and sTCC. In leukocytes, the venom of B. jararaca reduced the expression of CD11b, CD14 and C5aR1. Inhibition of the C3 component by Cp40, an inhibitor of C3, resulted in a reduction of C3a/C3a-desArg, C5a/C5a-desArg and sTCC to basal levels in samples stimulated with the venom. Exposure to B. jararaca venom induced the production of inflammatory cytokines and chemokines such as TNF-α, IL-8/CXCL8, MCP-1/CCL2 and MIG/CXCL9 in the human whole blood model. Treatment with Cp40 promoted a significant reduction in the production of TNF-α, IL-8/CXCL8 and MCP-1/CCL2. C5aR1 inhibition with PMX205 also promoted a reduction of TNF-α and IL-8/CXCL8 to basal levels in the samples stimulated with venom. In conclusion, the data presented here suggest that the activation of the complement system promoted by the venom of the snake B. jararaca in the human whole blood model significantly contributes to the inflammatory process. The control of several inflammatory parameters using Cp40, an inhibitor of the C3 component, and PMX205, a C5aR1 antagonist, indicates that complement inhibition may represent a potential therapeutic tool in B. jararaca envenoming.

Anti-SARS-CoV-2 equine F (Ab')2 immunoglobulin as a possible therapy for COVID-19.

The new outbreak of coronavirus disease 2019 (COVID-19) has infected and caused the death of millions of people worldwide. Intensive efforts are underway around the world to establish effective treatments. Immunoglobulin from immunized animals or plasma from convalescent patients might constitute a specific treatment to guarantee the neutralization of the virus in the early stages of infection, especially in patients with risk factors and a high probability of progressing to severe disease. Worldwide, a few clinical trials using anti-SARS-CoV-2 immunoglobulins from horses immunized with the entire spike protein or fragments of it in the treatment of patients with COVID-19 are underway. Here, we describe the development of an anti-SARS-CoV-2 equine F(ab')2 immunoglobulin using a newly developed SARS-CoV-2 viral antigen that was purified and inactivated by radiation. Cell-based and preclinical assays showed that the F(ab')2 immunoglobulin successfully neutralizes the virus, is safe in animal models, and reduces the severity of the disease in a hamster model of SARS-CoV-2 infection and disease.

New Insights into the Hypotensins from Tityus serrulatus Venom: Pro-Inflammatory and Vasopeptidases Modulation Activities.

The Tityus serrulatus scorpion is considered the most dangerous of the Brazilian fauna due to the severe clinical manifestations in injured victims. Despite being abundant components of the venom, few linear peptides have been characterized so far, such as hypotensins. In vivo studies have demonstrated that hypotensin I (TsHpt-I) exerts hypotensive activity, with an angiotensin-converting enzyme (ACE)-independent mechanism of action. Since experiments have not yet been carried out to analyze the direct interaction of hypotensins with ACE, and to deepen the knowledge about these peptides, hypotensins I and II (TsHpt-II) were studied regarding their modulatory action over the activities of ACE and neprilysin (NEP), which are the peptidases involved in blood pressure control. Aiming to search for indications of possible pro-inflammatory action, hypotensins were also analyzed for their role in murine macrophage viability, the release of interleukins and phagocytic activity. TsHpt-I and -II were used in kinetic studies with the metallopeptidases ACE and NEP, and both hypotensins were able to increase the activity of ACE. TsHpt-I presented itself as an inhibitor of NEP, whereas TsHpt-II showed weak inhibition of the enzyme. The mechanism of inhibition of TsHpt-I in relation to NEP was defined as non-competitive, with an inhibition constant (Ki) of 4.35 µM. Concerning the analysis of cell viability and modulation of interleukin levels and phagocytic activity, BALB/c mice's naïve macrophages were used, and an increase in TNF production in the presence of TsHpt-I and -II was observed, as well as an increase in IL-6 production in the presence of TsHpt-II only. Both hypotensins were able to increase the phagocytic activity of murine macrophages in vitro. The difference between TsHpt-I and -II is the residue at position 15, with a glutamine in TsHpt-I and a glutamic acid in TsHpt-II. Despite this, kinetic analyzes and cell assays indicated different actions of TsHpt-I and -II. Taken together, these results suggest a new mechanism for the hypotensive effects of TsHpt-I and -II. Furthermore, the release of some interleukins also suggests a role for these peptides in the venom inflammatory response. Even though these molecules have been well studied, the present results suggest a new mechanism for the hypotensive effects of TsHpt-I.

P-MAPA, a Fungi-Derived Immunomodulatory Compound, Induces a Proinflammatory Response in a Human Whole Blood Model.

P-MAPA is a complex compound, derived from Aspergillus oryzae cultures, that has shown immunomodulatory properties in infection and cancer animal models. Despite promising results in these models, the mechanisms of cellular activation by P-MAPA, suggested to be Toll-like receptor- (TLR-) dependent, and its effect on human immune cells, remain unclear. Using an ex vivo model of human whole blood, the effects of P-MAPA on complement system activation, production of cytokines, and the expression of complement receptors (CD11b, C5aR, and C3aR), TLR2, TLR4, and the coreceptor CD14 were analyzed in neutrophils and monocytes. P-MAPA induced complement activation in human blood, detected by increased levels of C3a, C5a, and SC5b-9 in plasma. As a consequence, CD11b expression increased and C5aR decreased upon activation, while C3aR expression remained unchanged in leukocytes. TLR2 and TLR4 expressions were not modulated by P-MAPA treatment on neutrophils, but TLR4 expression was reduced in monocytes, while CD14 expression increased in both cell types. P-MAPA also induced the production of TNF-α, IL-8, and IL-12 and oxidative burst, measured by peroxynitrite levels, in human leukocytes. Complement inhibition with compstatin showed that P-MAPA-induced complement activation drives modulation of C5aR, but not of CD11b, suggesting that P-MAPA acts through both complement-dependent and complement-independent mechanisms. Compstatin also significantly reduced the peroxynitrite generation. Altogether, our results show that P-MAPA induced proinflammatory response in human leukocytes, which is partially mediated by complement activation. Our data contribute to elucidate the complement-dependent and complement-independent mechanisms of P-MAPA, which ultimately result in immune cell activation and in its immunomodulatory properties in infection and cancer animal models.

Clinical aspects, diagnosis and management of Loxosceles spider envenomation: literature and case review.

The genus Loxosceles comprises 140 species widely distributed around the world. These spiders are nocturnal, sedentary and remarkably nonaggressive, although they cause accidents in humans with wide degrees of severity, generating signs and symptoms that define the clinical condition known as loxoscelism. Its local signs and symptoms were first reported in 1872, and over the years, a large medical literature has been accumulated; unfortunately, it is not always trustworthy. Assessing the reliability of such information, we reviewed 120 case reports of loxoscelism published in 84 articles over the past 20 years. This search allowed us to gather information on the clinical aspects, diagnosis and treatment of loxoscelism, showing that the severity of these accidents has multiple degrees and that it is influenced by many factors. Thus, coupled with epidemiological and species occurrence information, this study can be a useful tool for the clinical practice of loxoscelism. It may support and provide a multidisciplinary view that should be taken into consideration when establishing the therapeutic approach in cases of Loxosceles envenomation.

Corrigendum: Complement System Inhibition Modulates the Pro-Inflammatory Effects of a Snake Venom Metalloproteinase.

[This corrects the article DOI: 10.3389/fimmu.2019.01137.].

Complement System Inhibition Modulates the Pro-Inflammatory Effects of a Snake Venom Metalloproteinase.

Envenomation by Bothrops snakes causes prominent local effects, including pain, oedema, local bleeding, blistering and necrosis, and systemic manifestations, such as hemorrhage, hypotension, shock and acute renal failure. These snake venoms are able to activate the complement system and induce the generation of anaphylatoxins, whose mechanisms include the direct cleavage of complement components by snake venom metalloproteinases and serine proteinases present in the venoms. A metalloproteinase able to activate the three complement pathways and generate active anaphylatoxins, named C-SVMP, was purified from the venom of Bothrops pirajai. Considering the inflammatory nature of Bothrops venoms and the complement-activation property of C-SVMP, in the present work, we investigated the inflammatory effects of C-SVMP in a human whole blood model. The role of the complement system in the inflammatory process and its modulation by the use of compstatin were also investigated. C-SVMP was able to activate the complement system in the whole blood model, generating C3a/C3a desArg, C5a/C5a desArg and SC5b-9. This protein was able to promote an increase in the expression of CD11b, CD14, C3aR, C5aR1, TLR2, and TLR4 markers in leukocytes. Inhibition of component C3 by compstatin significantly reduced the production of anaphylatoxins and the Terminal Complement Complex (TCC) in blood plasma treated with the toxin, as well as the expression of CD11b, C3aR, and C5aR on leukocytes. C-SVMP was able to induce increased production of the cytokines IL-1ß and IL-6 and the chemokines CXCL8/IL-8, CCL2/MCP-1, and CXCL9/MIG in the human whole blood model. The addition of compstatin to the reactions caused a significant reduction in the production of IL-1ß, CXCL8/IL-8, and CCL2/MCP-1 in cells treated with C-SVMP. We therefore conclude that C-SVMP is able to activate the complement system, which leads to an increase in the inflammatory process. The data obtained with the use of compstatin indicate that complement inhibition may significantly control the inflammatory process initiated by Bothrops snake venom toxins.

Quality of horse F(ab')2 antitoxins and anti-rabies immunoglobulins: protein content and anticomplementary activity.

BACKGROUND: Among other applications, immunotherapy is used for the post-exposure treatment and/or prophylaxis of important infectious diseases, such as botulism, diphtheria, tetanus and rabies. The effectiveness of serum therapy is widely proven, but improvements on the immunoglobulin purification process and on the quality control are necessary to reduce the amount of protein aggregates. These may trigger adverse reactions in patients by activating the complement system and inducing the generation of anaphylatoxins. Herein, we used immunochemical methods to predict the quality of horse F(ab')2 anti-botulinum AB, anti-diphtheric, antitetanic and anti-rabies immunoglobulins, in terms of amount of proteins and protein aggregates. METHODS: Samples were submitted to protein quantification, SDS-PAGE, Western blot analysis and molecular exclusion chromatography. The anticomplementary activity was determined in vitro by detecting the production of C5a/C5a desArg, the most potent anaphylatoxin. Data were analyzed by one-way ANOVA followed by Tukey's post-test, and differences were considered statistically significant when p < 0.05. RESULTS: Horse F(ab')2 antitoxins and anti-rabies immunoglobulin preparations presented different amounts of protein. SDS-PAGE and Western blot analyses revealed the presence of protein aggregates, non-immunoglobulin contaminants and, unexpectedly, IgG whole molecules in the samples, indicating the non-complete digestion of immunoglobulins. The chromatographic profiles of antitoxins and anti-rabies immunoglobulins allowed to estimate the percentage of contaminants and aggregates in the samples. Although protein aggregates were present, the samples were not able to induce the generation of C5a/C5a desArg in vitro, indicating that they probably contain acceptable levels of aggregates. CONCLUSIONS: Anti-botulinum AB (bivalent), anti-diphtheric, antitetanic and anti-rabies horse F(ab')2 immunoglobulins probably contain acceptable levels of aggregates, although other improvements on the preparations must be carried out. Protein profile analysis and in vitro anticomplementary activity of F(ab')2 immunoglobulin preparations should be included as quality control steps, to ensure acceptable levels of aggregates, contaminants and whole IgG molecules on final products, reducing the chances of adverse reactions in patients.

The history of antivenoms development: Beyond Calmette and Vital Brazil.

This review presents the main contributions to our knowledge regarding the development of antivenoms for therapeutic use in victims of venomous animal bites. We cover the progress of serum therapy since tetanus and diphtheria antitoxins in Germany and France until the current scenario of antivenom production worldwide. During these more than 120 years of antivenom development, many researchers contributed to establish what are nowadays the antivenoms used for therapeutic purpose. The history of antivenoms development is fascinating! This review aims to recognize all those who contributed to the establishment of new sera, new methodologies and saving lives: much more than Calmette and Vital Brazil.

Loxosceles venom Sphingomyelinase D activates human blood leukocytes: Role of the complement system.

Envenomation by Loxosceles spiders can result in severe systemic and local reactions, which are mainly triggered by Sphingomyelinase D (SMase D), a toxic component of Loxosceles venom. SMase D induces a systemic inflammatory condition similar to the reaction observed during an endotoxic shock. Considering the potent pro-inflammatory potential of Loxosceles venom and the SMase D, in this study we have used the whole human blood model to study the endotoxic-like shock triggered by SMase D. Recombinant purified SMase D from L. intermedia venom, similarly to LPS, induced activation of blood leukocytes, as observed by the increase in the expression of CD11b and TLR4, production of reactive oxygen and nitrogen species (superoxide anion and peroxynitrite) and release of TNF-α. Complement consumption in the plasma was also detected, and complement inhibition by compstatin decreased the SMase D and LPS-induced leukocyte activation, as demonstrated by a reduction in the expression of CD11b and TLR4 and superoxide anion production. Similar results were found for the L. intermedia venom, except for the production of TNF-α. These findings indicate that SMase D present in Loxosceles venom is able to activate leukocytes in a partially complement-dependent manner, which can contribute to the systemic inflammation that follows envenomation by this spider. Thus, future therapeutic management of systemic Loxosceles envenomation could include the use of complement inhibitors as adjunct therapy.

Quality of horse F(ab')2 antitoxins and antirabies immunoglobulins: protein content and anticomplementary activity

Among other applications, immunotherapy is used for the post-exposure treatment and/or prophylaxis of important infectious diseases, such as botulism, diphtheria, tetanus and rabies. The effectiveness of serum therapy is widely proven, but improvements on the immunoglobulin purification process and on the quality control are necessary to reduce the amount of protein aggregates. These may trigger adverse reactions in patients by activating the complement system and inducing the generation of anaphylatoxins. Herein, we used immunochemical methods to predict the quality of horse F(ab′)2 anti-botulinum AB, anti-diphtheric, antitetanic and anti-rabies immunoglobulins, in terms of amount of proteins and protein aggregates. Methods Samples were submitted to protein quantification, SDS-PAGE, Western blot analysis and molecular exclusion chromatography. The anticomplementary activity was determined in vitro by detecting the production of C5a/C5a desArg, the most potent anaphylatoxin. Data were analyzed by one-way ANOVA followed by Tukey's post-test, and differences were considered statistically significant when p < 0.05. Results Horse F(ab′)2 antitoxins and anti-rabies immunoglobulin preparations presented different amounts of protein. SDS-PAGE and Western blot analyses revealed the presence of protein aggregates, non-immunoglobulin contaminants and, unexpectedly, IgG whole molecules in the samples, indicating the non-complete digestion of immunoglobulins. The chromatographic profiles of antitoxins and anti-rabies immunoglobulins allowed to estimate the percentage of contaminants and aggregates in the samples. Although protein aggregates were present, the samples were not able to induce the generation of C5a/C5a desArg in vitro, indicating that they probably contain acceptable levels of aggregates. Conclusions Anti-botulinum AB (bivalent), anti-diphtheric, antitetanic and anti-rabies horse F(ab′)2 immunoglobulins probably contain acceptable levels of aggregates, although other improvements on the preparations must be carried out. Protein profile analysis and in vitro anticomplementary activity of F(ab′)2 immunoglobulin preparations should be included as quality control steps, to ensure acceptable levels of aggregates, contaminants and whole IgG molecules on final products, reducing the chances of adverse reactions in patients.(AU)

Quality of horse F(ab)2 antitoxins and antirabies immunoglobulins: protein content and anticomplementary activity

Background Among other applications, immunotherapy is used for the post-exposure treatment and/or prophylaxis of important infectious diseases, such as botulism, diphtheria, tetanus and rabies. The effectiveness of serum therapy is widely proven, but improvements on the immunoglobulin purification process and on the quality control are necessary to reduce the amount of protein aggregates. These may trigger adverse reactions in patients by activating the complement system and inducing the generation of anaphylatoxins. Herein, we used immunochemical methods to predict the quality of horse F(ab)2 anti-botulinum AB, anti-diphtheric, antitetanic and anti-rabies immunoglobulins, in terms of amount of proteins and protein aggregates. Methods Samples were submitted to protein quantification, SDS-PAGE, Western blot analysis and molecular exclusion chromatography. The anticomplementary activity was determined in vitro by detecting the production of C5a/C5a desArg, the most potent anaphylatoxin. Data were analyzed by one-way ANOVA followed by Tukey's post-test, and differences were considered statistically significant when p 0.05. Results Horse F(ab)2 antitoxins and anti-rabies immunoglobulin preparations presented different amounts of protein. SDS-PAGE and Western blot analyses revealed the presence of protein aggregates, non-immunoglobulin contaminants and, unexpectedly, IgG whole molecules in the samples, indicating the non-complete digestion of immunoglobulins. The chromatographic profiles of antitoxins and anti-rabies immunoglobulins allowed to estimate the percentage of contaminants and aggregates in the samples. Although protein aggregates were present, the samples were not able to induce the generation of C5a/C5a desArg in vitro, indicating that they probably contain acceptable levels of aggregates...

Modulation of Th1/Th2 immune responses by killed Propionibacterium acnes and its soluble polysaccharide fraction in a type I hypersensitivity murine model: induction of different activation status of antigen-presenting cells.

Propionibacterium acnes (P. acnes) is a gram-positive anaerobic bacillus present in normal human skin microbiota, which exerts important immunomodulatory effects, when used as heat- or phenol-killed suspensions. We previously demonstrated that heat-killed P. acnes or its soluble polysaccharide (PS), extracted from the bacterium cell wall, suppressed or potentiated the Th2 response to ovalbumin (OVA) in an immediate hypersensitivity model, depending on the treatment protocol. Herein, we investigated the mechanisms responsible for these effects, using the same model and focusing on the activation status of antigen-presenting cells (APCs). We verified that higher numbers of APCs expressing costimulatory molecules and higher expression levels of these molecules are probably related to potentiation of the Th2 response to OVA induced by P. acnes or PS, while higher expression of toll-like receptors (TLRs) seems to be related to Th2 suppression. In vitro cytokines production in cocultures of dendritic cells and T lymphocytes indicated that P. acnes and PS seem to perform their effects by acting directly on APCs. Our data suggest that P. acnes and PS directly act on APCs, modulating the expression of costimulatory molecules and TLRs, and these differently activated APCs drive distinct T helper patterns to OVA in our model.

Anticomplementary activity of horse IgG and F(ab')2 antivenoms.

Envenomation by poisonous animals is a neglected condition according to the World Health Organization (WHO). Antivenoms are included in the WHO Essential Medicines List. It has been assumed that immunoglobulin G (IgG) antivenoms could activate the complement system through Fc and induce early adverse reactions (EARs). However, data in the literature indicate that F(ab')2 fragments can also activate the complement system. Herein, we show that several batches of IgG and F(ab')2 antivenoms from the Butantan, Vital Brazil, and Clodomiro Picado Institutes activated the complement classical pathway and induced the production of C3a; however, only those antivenoms from Clodomiro Picado generated C5a. Different protein profiles (IgG heavy chain, protein contaminants, and aggregates) were observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analyses. Our results show that various antivenoms from different producers are able to activate the classical pathway of the complement system and generate anaphylatoxins, and these findings suggest that factors, such as composition, contaminant proteins, and aggregates, may influence the anticomplementary activity of antivenoms in vitro. Therefore, there is a need to further improve antivenom production methods to reduce their anticomplementary activity and potential to cause EARs.

Characterization of phenotypes of immune cells and cytokines associated with chronic exposure to Premolis semirufa caterpillar bristles extract.

The Brazilian moth Premolis semirufa (Walker, 1856), usually called pararama, is a parasite of the rubber Hevea genus. Contact with the bristles causes symptoms of acute inflammation. A chronic inflammatory reaction frequently occurs in individuals after multiple contacts, and this reaction is characterised by articular synovial membrane thickening with joint deformities, common characteristics of chronic synovitis. Extract from the bristles has been shown to induce an intense inflammatory response in a murine model, and this reaction was characterised by the presence of neutrophils in the paw tissues of injected mice and a strong, specific antibody response. There is not yet an effective treatment for incidents involving contact with pararama. In this study, we evaluated the phenotype of the immunological response and cytokine production in BALB/c mice subcutaneously injected in the footpad with P. semirufa bristle extract or sterile saline (control) seven times at 15 day intervals. An analysis of cells from the draining lymph node by flow cytometry showed that the absolute numbers of TCD4, TCD8 and B lymphocytes, as well as the expression of activation molecules, were higher in the extract-treated group. Furthermore, immunohistochemistry and immunofluorescence analyses showed a mixed inflammatory infiltrate composed of neutrophils and macrophages at the inoculation site. In addition, an analysis of paw cytokines showed elevated levels of IL-6, IL-12, IL-10, IL-17 and IL-23 after the 7(th) inoculation. In conclusion, these data provide evidence of pro-inflammatory changes in the phenotypes of immune cells and cytokine production in animals subjected to injections with an extract from Premolis semirufa bristles, which may explain the intense and prolonged inflammatory response that characterises this disorder.

Increased bone loss and amount of osteoclasts in kinin B1 receptor knockout mice.

AIM: The pathophysiology of periodontal diseases involves aspects of immunity and bone remodelling. Considering the role of the kinin B1 receptor (Bdkrb1) in inflammation and healing, the purpose of this study was to evaluate the contribution of Bdkrb1 to the pathogenesis of periodontitis. MATERIAL AND METHODS: We used a model of ligature-induced experimental periodontitis (LIEP) in mice lacking Bdkrb1 (Bdkrb1(-/-) ) to test the role of this receptor in bone loss and cytokine secretion by lymph nodes cells. Angiotensin-converting enzyme inhibitor (ACEi) was used as a pharmacological strategy to support the genetic model. Also, autonomous effect of Bdkrb1 deletion was evaluated in osteoclasts precursors from bone marrow. RESULTS: Bdkrb1(-/-) mice exhibit increased bone loss and IL-17 secretion in response to LIEP when compared to wild type. LIEP does not modify TNF-α, IFN-γ and IL-10 levels in Bdkrb1(-/-) mice after 21 days. Bone marrow cells from Bdkrb1(-/-) displayed increased differentiation into functional osteoclasts with consistent artificial calcium phosphate degradation. Furthermore, treatment of mice with ACEi prevented bone destruction. CONCLUSION: Bdkrb1 participates in the pathogenesis of LIEP bone loss possibly through mechanisms that involve modulation of the TH 17 response, thereby demonstrating its role in the development of periodontitis.

Adjuvant effect of killed Propionibacterium acnes on mouse peritoneal B-1 lymphocytes and their early phagocyte differentiation.

B-1 lymphocytes are the predominant cells in mouse peritoneal cavity. They express macrophage and lymphocyte markers and are divided into B-1a, B-1b and B-1c subtypes. The role of B-1 cells is not completely clear, but they are responsible for natural IgM production and seem to play a regulatory role. An enriched B-1b cell population can be obtained from non-adherent peritoneal cell cultures, and we have previously demonstrated that these cells undergo differentiation to acquire a mononuclear phagocyte phenotype upon attachment to the substrate in vitro. Nevertheless, the B-1 cell response to antigens or adjuvants has been poorly investigated. Because killed Propionibacterium acnes exhibits immunomodulatory effects on both macrophages and B-2 lymphocytes, we analyzed whether a killed bacterial suspension or its soluble polysaccharide (PS) could modulate the absolute number of peritoneal B-1 cells in BALB/c mice, the activation status of these cells and their ability to differentiate into phagocytes in vitro. In vivo, P. acnes treatment elevated the absolute number of all B-1 subsets, whereas PS only increased B-1c. Moreover, the bacterium increased the number of B-1b cells that were positive for MHC II, TLR2, TLR4, TLR9, IL-4, IL-5 and IL-12, in addition to up-regulating TLR9, CD80 and CD86 expression. PS increased B-1b cell expression of TLR4, TLR9, CD40 and CD86, as well as IL-10 and IL-12 synthesis. Both of the treatments decreased the absolute number of B-1b cells in vitro, suggesting their early differentiation into B-1 cell-derived phagocytes (B-1CDP). We also observed a higher phagocytic activity from the phagocytes that were derived from B-1b cells after P. acnes and PS treatment. The adjuvant effect that P. acnes has on B-1 cells, mainly the B-1b subtype, reinforces the importance of B-1 cells in the innate and adaptive immune responses.