Lack of galectin-3 drives response to Paracoccidioides brasiliensis toward a Th2-biased immunity

Elevated cerebrospinal fluid galectin-3 and associated cytokines after severe traumatic brain injury in patients

This study aimed to investigate the galectin-3 and associated cytokines levels in the cerebrospinal fluid (CSF) of severe traumatic brain injury (sTBI) patients. Temporal CSF expression of galectin-3 and associated cytokines levels in sTBI patients within 1-week post-injury were studied using the multiplex bead array. STBI patient group was stratified using the Modified Rankin Score (mRS) into 3 groups: mRS 6 (died), mRS 5 (severely disabled) and mRS 1-4 (mild-to-moderately disabled) group. Analysis for bead array data using Kruskal-Wallis test with post hoc Dunn's multiple comparisons test, and temporal changes and correlation analysis using Spearman's correlation were carried out. At day 1 post-injury, CSF galectin-3 and interleukin-6 (IL-6), interleukin-10 (IL-10), cysteine-cysteine motif chemokine ligand-2 (CCL-2), and cysteine-cysteine motif chemokine ligand-20 (CCL-20), but not interleukin-1β (IL-1β) and tumor necrosis factor (TNF-α) levels were significantly elevated in mRS 5 group compared to non-TBI controls. Temporal correlation analysis at 1-7 days showed decreased IL-10 level in the mRS 6 group, decreased IL-10 and CCL-2 levels in mRS 5 group, and decreased IL-6, CCL-2, and CCL-20 levels in the mRS 1-4 group. Receiver operating characteristic curve analyses revealed a significant area under the curve for comparison between mRS 6 and mRS 5 groups for galectin-3 and IL-6. No significant differences in sex, age, Glasgow Coma Scale score, C-reactive protein levels and types of TBI-induced hemorrhages were observed between the groups. CSF galectin-3 and associated cytokines, especially IL-6, CCL-2 and CCL-20 levels were different within sub-groups of sTBI patients, suggesting their potential use in sTBI prognostics.

Galectin-3 expression in donor T cells reduces GvHD severity and lethality after allogeneic hematopoietic cell transplantation

Abundant donor cytotoxic T cells that attack normal host organs remain a major problem for patients receiving allogeneic hematopoietic cell transplantation (allo-HCT). Despite an increase in our knowledge of the pathobiology of acute graft versus host disease (aGvHD), the mechanisms regulating the proliferation and function of donor T cells remain unclear. Here, we show that activated donor T cells express galectin-3 (Gal-3) after allo-HCT. In both major and minor histocompatibility-mismatched models of murine aGvHD, expression of Gal-3 is associated with decreased T cell activation and suppression of the secretion of effector cytokines, including IFN-γ and GM-CSF. Mechanistically, Gal-3 results in activation of NFAT signaling, which can induce T cell exhaustion. Gal-3 overexpression in human T cells prevents severe disease by suppressing cytotoxic T cells in xenogeneic aGvHD models. Together, these data identify the Gal-3-dependent regulatory pathway in donor T cells as a critical component of inflammation in aGvHD.

Influence of Galectin-3 on the Innate Immune Response during Experimental Cryptococcosis

Cryptococcus neoformans, the causative agent of cryptococcosis, is the primary fungal pathogen that affects the immunocompromised individuals. Galectin-3 (Gal-3) is an animal lectin involved in both innate and adaptive immune responses. The present study aimed to evaluate the influence of Gal-3 on the C. neoformans infection. We performed histopathological and gene profile analysis of the innate antifungal immunity markers in the lungs, spleen, and brain of the wild-type (WT) and Gal-3 knockout (KO) mice during cryptococcosis. These findings suggest that Gal-3 absence does not cause significant histopathological alterations in the analyzed tissues. The expression profile of the genes related to innate antifungal immunity showed that the presence of cryptococcosis in the WT and Gal-3 KO animals, compared to their respective controls, promoted the upregulation of the pattern recognition receptor (PRR) responsive to mannose/chitin (mrc1) and a gene involved in inflammation (ccr5), as well as the downregulation of the genes related to signal transduction (card9, fos, ikbkb, jun) and PRRs (cd209a, colec12, nptx1). The absence of Gal-3, in fungal infection, a positively modulated gene involved in phagocytosis (sftpd) and negatively genes involved in signal transduction (syk and myd88), proinflammatory cytokines il-1β and il-12b and cd209a receptor. Therefore, our results suggest that Gal-3 may play an essential role in the development of antifungal immune responses against cryptococcosis.

The Role of IL-17-Producing Cells in Cutaneous Fungal Infections

The skin is the outermost layer of the body and is exposed to many environmental stimuli, which cause various inflammatory immune responses in the skin. Among them, fungi are common microorganisms that colonize the skin and cause cutaneous fungal diseases such as candidiasis and dermatophytosis. The skin exerts inflammatory responses to eliminate these fungi through the cooperation of skin-component immune cells. IL-17 producing cells are representative immune cells that play a vital role in anti-fungal action in the skin by producing antimicrobial peptides and facilitating neutrophil infiltration. However, the actual impact of IL-17-producing cells in cutaneous fungal infections remains unclear. In this review, we focused on the role of IL-17-producing cells in a series of cutaneous fungal infections, the characteristics of skin infectious fungi, and the recognition of cell components that drive cutaneous immune cells.

Altered expression of genes related to innate antifungal immunity in the absence of galectin-3

Galectin-3 (Gal-3) is the most studied member of the animal galectin family, which comprises β-galactoside-binding lectins and participates in several cellular events. Its expression in cells involved in innate and adaptive immunity is related to anti- and proinflammatory functions, signaling an important role in inflammatory, infectious, and tumorigenesis processes. Mice deficient in Gal-3 exhibit important phenotypes, but it is unclear whether these phenotypes reflect an impairment of the functions of this protein. Gal-3 plays an important role in modulating the immune response to different pathogenic microorganisms. However, the role of Gal-3 in immunity to infection is still poorly understood. Therefore, we investigated the effects of Gal-3 deletion on the expression of genes involved in the innate immune response in the lungs, spleens, and brains of Gal-3 KO mice. Gene profiling expression analysis suggested that Gal-3 deletion resulted in differentially modulated expression of the genes encoding beta-glucan, mannose and chitin-responsive pattern recognition receptors, signal transduction, inflammation, and phagocytosis. Our data thus suggest the importance of Gal-3 expression in the host innate immune system.

Silva L, Gonçales RA, Neves BJ, Soares CM, Pereira M. Setting New Routes for Antifungal Drug Discovery Against Pathogenic Fungi

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Fungal diseases are life-threatening to human health and responsible for millions of deaths around the world. Fungal pathogens lead to a high number of morbidity and mortality. Current antifungal treatment comprises drugs, such as azoles, echinocandins, and polyenes and the cure is not guaranteed. In addition, such drugs are related to severe side effects and the treatment lasts for an extended period. Thus, setting new routes for the discovery of effective and safe antifungal drugs should be a priority within the health care system. The discovery of alternative and efficient antifungal drugs showing fewer side effects is time-consuming and remains a challenge. Natural products can be a source of antifungals and used in combinatorial therapy. The most important natural products are antifungal peptides, antifungal lectins, antifungal plants, and fungi secondary metabolites. Several proteins, enzymes, and metabolic pathways could be targets for the discovery of efficient inhibitor compounds and recently, heat shock proteins, calcineurin, salinomycin, the trehalose biosynthetic pathway, and the glyoxylate cycle have been investigated in several fungal species. HSP protein inhibitors and echinocandins have been shown to have a fungicidal effect against azole-resistant fungi strains. Transcriptomic and proteomic approaches have advanced antifungal drug discovery and pointed to new important specific-pathogen targets. Certain enzymes, such as those from the glyoxylate cycle, have been a target of antifungal compounds in several fungi species. Natural and synthetic compounds inhibited the activity of such enzymes and reduced the ability of fungal cells to transit from mycelium to yeast, proving to be promisor antifungal agents. Finally, computational biology has developed effective approaches, setting new routes for early antifungal drug discovery since normal approaches take several years from discovery to clinical use. Thus, the development of new antifungal strategies might reduce the therapeutic time and increase the quality of life of patients.

Mucosal Vaccination with Lactococcus lactis-Secreting Surface Immunological Protein Induces Humoral and Cellular Immune Protection against Group B Streptococcus in a Murine Model

Group B Streptococcus (GBS) is the primary etiological agent of sepsis and meningitis in newborns and is associated with premature birth and stillbirth. The development of a licensed vaccine is one of the pending challenges for the World Health Organization. Previously, we showed that oral immunization with surface immune protein (SIP) decreases vaginal colonization of GBS and generates functional opsonizing antibodies, which was determined by opsonophagocytic assays (OPA) in vitro. We also showed that the protein has an adjuvant vaccine profile. Therefore, an oral vaccine based on SIP may be an attractive alternative to employ in the development of new vaccines against GBS. Lactococcus lactis is a highlighted oral vaccine probiotic inducer of the mucosal immune response. This bacterium could serve as an antigen-delivering vehicle for the development of an edible vaccine and has been used in clinical trials. In this study, we showed that an oral vaccine with a recombinant L. lactis strain secreting SIP from GBS (rL. lactis-SIP) can induce protective humoral and cellular immunity in an experimental model of GBS vaginal colonization in C57BL/6 mice. Mice immunized with rL. lactis-SIP were protected against clinical symptoms and bacterial colonization after GBS vaginal colonization. Our rL. lactis-SIP vaccine also induces an increase of immunoglobulin G (IgG) and immunoglobulin A (IgA) specifically against SIP. The adoptive transfer of serum from vaccinated mice to naïve mice generated protection against GBS vaginal colonization. Moreover, the rL.lactis-SIP strain induces the activation of SIP-specific T cells, which could decrease GBS vaginal colonization and generate protective antibodies when transferred to other mice. Our experimental observations strongly support the notion that rL. lactis-SIP induces protective humoral and cellular immunity and could be considered as a novel alternative in the development of vaccines for GBS.

Galectins in Host-Pathogen Interactions: Structural, Functional and Evolutionary Aspects

Galectins are a family of ß-galactoside-binding lectins characterized by a unique sequence motif in the carbohydrate recognition domain, and evolutionary and structural conservation from fungi to invertebrates and vertebrates, including mammals. Their biological roles, initially understood as limited to recognition of endogenous ("self") carbohydrate ligands in embryogenesis and early development, dramatically expanded in later years by the discovery of their roles in tissue repair, cancer, adipogenesis, and regulation of immune homeostasis. In recent years, however, evidence has also accumulated to support the notion that galectins can bind ("non-self") glycans on the surface of potentially pathogenic microbes, and function as recognition and effector factors in innate immunity. Thus, this evidence has established a new paradigm by which galectins can function not only as pattern recognition receptors but also as effector factors, by binding to the microbial surface and inhibiting adhesion and/or entry into the host cell, directly killing the potential pathogen by disrupting its surface structures, or by promoting phagocytosis, encapsulation, autophagy, and pathogen clearance from circulation. Strikingly, some viruses, bacteria, and protistan parasites take advantage of the aforementioned recognition roles of the vector/host galectins, for successful attachment and invasion. These recent findings suggest that galectin-mediated innate immune recognition and effector mechanisms, which throughout evolution have remained effective for preventing or fighting viral, bacterial, and parasitic infection, have been "subverted" by certain pathogens by unique evolutionary adaptations of their surface glycome to gain host entry, and the acquisition of effective mechanisms to evade the host's immune responses.

Galectin-3 Inhibits Paracoccidioides brasiliensis Growth and Impacts Paracoccidioidomycosis through Multiple Mechanisms

The thermodimorphic pathogenic fungi Paracoccidioides brasiliensis and Paracoccidioides lutzii are the etiologic causes of paracoccidioidomycosis (PCM), the most prevalent systemic mycosis in Latin America. Galectin-3 (Gal-3), an animal β-galactoside-binding protein, modulates important roles during microbial infections, such as triggering a Th2-polarized immune response in PCM. Herein, we demonstrate that Gal-3 also plays other important roles in P. brasiliensis infection. We verified that Gal-3 levels are upregulated in human and mice infections and established that Gal-3 inhibited P. brasiliensis growth by inhibiting budding. Furthermore, Gal-3 affected disruption and internalization of extracellular vesicles (EVs) from P. brasiliensis by macrophages. Our results suggest important protective roles for Gal-3 in P. brasiliensis infection, indicating that increased Gal-3 production during P. brasiliensis infection may affect fungal growth and EV stability, thus promoting beneficial effects that could influence the course of PCM. The finding that Gal-3 has effects against P. brasiliensis together with previously reported effects against Cryptococcus neoformans suggests that molecule has a general antifungal role in innate defenses against fungal pathogens.IMPORTANCE Paracoccidioidomycosis (PCM) is the most prevalent systemic mycosis in Latin America. Although the immune mechanisms to control PCM are still not fully understood, several events of the host innate and adaptive immunity are crucial to determine the progress of the infection. Mammalian β-galactoside-binding protein galectin-3 (Gal-3) plays significant roles during microbial infections and has been studied for its immunomodulatory roles, but it can also have direct antimicrobial effects. We asked whether this protein plays a role in Paracoccidioides brasiliensis We report herein that Gal-3 indeed has direct effects on the fungal pathogen, inhibiting fungal growth and reducing extracellular vesicle stability. Our results suggest a direct role for Gal-3 in P. brasiliensis infection, with beneficial effects for the mammalian host.

The Role of Collectins and Galectins in Lung Innate Immune Defense

Different families of endogenous lectins use complementary defense strategies against pathogens. They may recognize non-self glycans typically found on pathogens and/or host glycans. The collectin and galectin families are prominent examples of these two lectin categories. Collectins are C-type lectins that contain a carbohydrate recognition domain and a collagen-like domain. Members of this group include surfactant protein A (SP-A) and D (SP-D), secreted by the alveolar epithelium to the alveolar fluid. Lung collectins bind to several microorganisms, which results in pathogen aggregation and/or killing, and enhances phagocytosis of pathogens by alveolar macrophages. Moreover, SP-A and SP-D influence macrophage responses, contributing to resolution of inflammation, and SP-A is essential for tissue-repair functions of macrophages. Galectins also function by interacting directly with pathogens or by modulating the immune system in response to the infection. Direct binding may result in enhanced or impaired infection of target cells, or can have microbicidal effects. Immunomodulatory effects of galectins include recruitment of immune cells to the site of infection, promotion of neutrophil function, and stimulation of the bactericidal activity of infected macrophages. Moreover, intracellular galectins can serve as danger receptors, promoting autophagy of the invading pathogen. This review will focus on the role of collectins and galectins in pathogen clearance and immune response activation in infectious diseases of the respiratory system.

Galectin-3 impacts Cryptococcus neoformans infection through direct antifungal effects

Cryptococcus neoformans is an encapsulated fungal pathogen that causes cryptococcosis, which is a major opportunistic infection in immunosuppressed individuals. Mammalian β-galactoside-binding protein Galectin-3 (Gal-3) modulates the host innate and adaptive immunity, and plays significant roles during microbial infections including some fungal diseases. Here we show that this protein plays a role also in C. neoformans infection. We find augmented Gal-3 serum levels in human and experimental infections, as well as in spleen, lung, and brain tissues of infected mice. Gal-3-deficient mice are more susceptible to cryptococcosis than WT animals, as demonstrated by the higher fungal burden and lower animal survival. In vitro experiments show that Gal-3 inhibits fungal growth and exerts a direct lytic effect on C. neoformans extracellular vesicles (EVs). Our results indicate a direct role for Gal-3 in antifungal immunity whereby this molecule affects the outcome of C. neoformans infection by inhibiting fungal growth and reducing EV stability, which in turn could benefit the host.

The Two Faces of Galectin-3: Roles in Various Pathological Conditions

Galectin-3, a unique chimaera-type member of the lectin family, displays a wide range of activities. This versatile molecule is involved in fundamental biological processes, including cell proliferation, cell-cell adhesion, apoptosis and immune responses.

This review is aimed at providing a general overview of the biological actions and diverse effects of Galectin-3 in many pathological conditions, with a specific focus on autoimmunity, inflammation and tumour progression. We report herein that Galectin-3 exerts deleterious functions determined by promotion of tumour progression and liver inflammation or aggravation of T cell-mediated autoimmune diseases. On the other hand, Galectin-3 exhibits a protective role in metabolic abnormalities and primary biliary cirrhosis.

The paradoxical “yin and yang” functions of Galectin-3 depend not only on its tissue and cellular localization but also on its availability, glycosylation status and the expression level of its ligands.

Lack of galectin-3 increases Jagged1/Notch activation in bone marrow-derived dendritic cells and promotes dysregulation of T helper cell polarization

Galectin-3, an endogenous glycan-binding protein, is abundantly expressed at sites of inflammation and immune cell activation. Although this lectin has been implicated in the control of T helper (Th) polarization, the mechanisms underlying this effect are not well understood. Here, we investigated the role of endogenous galectin-3 during the course of experimental Leishmania major infection using galectin-3-deficient (Lgals3(-/-)) mice in a BALB/c background and the involvement of Notch signaling pathway in this process. Lgals3(-/-) mice displayed an augmented, although mixed Th1/Th2 responses compared with wild-type (WT) mice. Concomitantly, lymph node and footpad lesion cells from infected Lgals3(-/-) mice showed enhanced levels of Notch signaling components (Notch-1, Jagged1, Jagged2 and Notch target gene Hes-1). Bone marrow-derived dendritic cells (BMDCs) from uninfected Lgals3(-/-) mice also displayed increased expression of the Notch ligands Delta-like-4 and Jagged1 and pro-inflammatory cytokines. In addition, activation of Notch signaling in BMDCs upon stimulation with Jagged1 was more pronounced in Lgals3(-/-) BMDCs compared to WT BMDCs; this condition resulted in increased production of IL-6 by Lgals3(-/-) BMDCs. Finally, addition of exogenous galectin-3 to Lgals3(-/-) BMDCs partially reverted the increased sensitivity to Jagged1 stimulation. Our results suggest that endogenous galectin-3 regulates Notch signaling activation in BMDCs and influences polarization of T helper responses, thus increasing susceptibility to L. major infection.

Association between circulating galectin-3 levels and the immunological, inflammatory and nutritional parameters in patients with colorectal cancer

Galectin-3, a β-galactoside-binding lectin, exhibits pleiotropic biological functions and has a role as one of the immunological modulators. However, the associations between circulating galectin-3 and immunological, inflammatory and nutritional parameters have not yet been fully elucidated. The serum concentration of galectin-3 was examined in association with interleukin-10 (IL-10), IL-12 and IL17 production, lymphocyte stimulation, neutrophil/lymphocyte ratio (NLR), white blood cell count (WBC), C-reactive protein (CRP) and rapid turnover proteins, including retinol-binding protein (RBP), prealbumin (PA) and transferrin (TF) in 50 patients with untreated colorectal cancers. Significant increases (P<0.05) were observed in the serum galectin-3 levels in patients with untreated colorectal cancer (9.6±4.5 ng/ml) compared with the normal controls (3.2±1.6 ng/ml). Higher serum galectin-3 concentrations were observed in patients with colon cancer (11.5±4.4 ng/ml) compared to in patients with rectal cancer (8.0±4.0 ng/ml) (P=0.005). The levels of circulating galectin-3 inversely correlated with the production of IL-10 (r=-0.59, P<0.001), and IL-12 (r=-0.69, P<0.001). Galectin-3 concentration also inversely correlated with the lymphocyte stimulation assay stimulation index (r=-0.42, P=0.021). However, the level of serum galectin-3 correlated with IL-17 production (r=0.67, P<0.001). Serum galectin-3 levels exhibited significant correlations with NLR (r=0.41, P=0.009), WBC (r=0.32, P=0.035), and CRP (r=0.63, P<0.001), and statistically significant inverse correlations with RBP (r=-0.45, P=0.002), PA (r=-0.46, P=0.001) and TF (r=-0.72, P<0.001). Galectin-3 may be one of the key factors in the regulation of immunological, inflammatory and nutritional conditions.

Allergens Induce the Release of Lactoferrin by Neutrophils from Asthmatic Patients

Background

Despite the evidence that Lactoferrin (Lf) is involved in allergic asthma processes, it is unknown whether neutrophils can be one of the main cellular sources of this key inflammatory mediator directly in response of an IgE mediated stimulus. The present study was undertaken to analyze this question.

Methods

Neutrophils from healthy subjects (n = 34) and neutrophils from allergic asthmatic patients (n = 102) were challenged in vitro with specific allergens to which the patients were sensitized, PAF, or agonist mAbs against IgE-receptors, and the levels of Lf were measured in the culture supernatant. The levels of serum IgE together with the severity of symptoms were also analyzed.

Results

Lf was released into the culture supernatant of neutrophils from allergic asthmatic patients in response to allergens and PAF. This response was highly allergen-specific, and did not happen in neutrophils from healthy donors. Allergen effect was mimicked by Abs against FcεRI and galectin-3 but not by FcεRII. The levels of released Lf correlated well with the levels of serum specific IgE and severity of asthma symptoms. These observations represent a novel view of neutrophils as an important source of Lf in allergic asthma. Importantly, the levels of released Lf by neutrophils could therefore be used to evaluate disease severity in allergic asthmatic patients.

Dendritic cell interactions with Histoplasma and Paracoccidioides

Fungi are among the most common microbes encountered by humans. More than 100, 000 fungal species have been described in the environment to date, however only a few species cause disease in humans. Fungal infections are of particular importance to immunocompromised hosts in whom disease is often more severe, especially in those with impaired cell-mediated immunity such as individuals with HIV infection, hematologic malignancies, or those receiving TNF-α inhibitors. Nevertheless, environmental disturbances through natural processes or as a consequence of deforestation or construction can expose immunologically competent people to a large number of fungal spores resulting in asymptomatic acquisition to life-threatening disease. In recent decades, the significance of the innate immune system and more importantly the role of dendritic cells (DC) have been found to play a fundamental role in the resolution of fungal infections, such as in dimorphic fungi like Histoplasma and Paracoccidioides. In this review article the general role of DCs will be illustrated as the bridge between the innate and adaptive immune systems, as well as their specific interactions with these 2 dimorphic fungi.

Saccharomyces cerevisiae expressing Gp43 protects mice against Paracoccidioides brasiliensis infection

The dimorphic fungus Paracoccidioides brasiliensis is the etiological agent of paracoccidioidomycosis (PCM). It is believed that approximately 10 million people are infected with the fungus and approximately 2% will eventually develop the disease. Unlike viral and bacterial diseases, fungal diseases are the ones against which there is no commercially available vaccine. Saccharomyces cerevisiae may be a suitable vehicle for immunization against fungal infections, as they require the stimulation of different arms of the immune response. Here we evaluated the efficacy of immunizing mice against PCM by using S. cerevisiae yeast expressing gp43. When challenged by inoculation of P. brasiliensis yeasts, immunized animals showed a protective profile in three different assays. Their lung parenchyma was significantly preserved, exhibiting fewer granulomas with fewer fungal cells than found in non-immunized mice. Fungal burden was reduced in the lung and spleen of immunized mice, and both organs contained higher levels of IL-12 and IFN-γ compared to those of non-vaccinated mice, a finding that suggests the occurrence of Th1 immunity. Taken together, our results indicate that the recombinant yeast vaccine represents a new strategy to confer protection against PCM.

Evaluation of in situ expression of effector and regulatory cytokines, TLR, galectins and matrix metalloproteinases in oral manifestations of paracoccidioidomycosis

BACKGROUND

Although the pathophysiology of paracoccidioidomycosis (PCM) is not completely understood, the study of immune response against fungus has provided insight into understanding the natural course of the disease and its clinical manifestations, hence contributing to the development of preventive measures and treatment proposals. The aim of this study was to evaluate the histopathological and immunological aspects involved in the role of different effector and regulatory responses, as well as the correlation between the TLRs, Galectins, Matrix Metalloproteinases and cytoplasmic proteases of mast cells in this infection.

METHODS

Sixteen biopsy specimens with oral lesions of chronic PCM, as well as 13 sections of normal oral mucosa were analyzed. Histopathological and immunological aspects involved in the role of different effector and regulatory responses were evaluated. Indirect immunohistochemistry was performed for IL-17, IL-10, IL-4, TGF-β, FoxP3, Gal-1, Gal-3, Gal-9, TLR-2, TLR-4, MMP-3 and MMP-9, as well as for chymase and tryptase for mast cells identification. Fibrosis was quantified using Picrosirius.

RESULTS

There was a significant increase in the area of fibrosis and in the number of cells expressing IL-10, IL-4, IL-17, FoxP3, Gal-3, TLR-2, MMP3 and MMP9 in patients with PCM in comparison with patients in the group control. There was no difference in the expression of TGF-β, TLR-4, Gal-1 or Gal-9. Mast cells number was found to be significantly lower in oral chronic PCM when compared to control samples after quantification of mast cells and expression of chymase and tryptase. PCM granulomas were classified to the morphological aspects in organized ou non-organized. Expression of IL-4 in non-organized granulomas was significantly higher.

CONCLUSION

The proteins studied herein appear to play an important role in the development and maintenance of oral lesions of PCM, as well as in the processes of development and progression of lesions caused by the fungus and by the immune response associated with the infection.

Recombinant paracoccin reproduces the biological properties of the native protein and induces protective Th1 immunity against Paracoccidioides brasiliensis infection

BACKGROUND

Paracoccin is a dual-function protein of the yeast Paracoccidioides brasiliensis that has lectin properties and N-acetylglucosaminidase activities. Proteomic analysis of a paracoccin preparation from P. brasiliensis revealed that the sequence matched that of the hypothetical protein encoded by PADG-3347 of isolate Pb-18, with a polypeptide sequence similar to the family 18 endochitinases. These endochitinases are multi-functional proteins, with distinct lectin and enzymatic domains.

METHODOLOGY/PRINCIPAL FINDINGS

The multi-exon assembly and the largest exon of the predicted ORF (PADG-3347), was cloned and expressed in Escherichia coli cells, and the features of the recombinant proteins were compared to those of the native paracoccin. The multi-exon protein was also used for protection assays in a mouse model of paracoccidioidomycosis.

CONCLUSIONS/SIGNIFICANCE

Our results showed that the recombinant protein reproduced the biological properties described for the native protein-including binding to laminin in a manner that is dependent on carbohydrate recognition-showed N-acetylglucosaminidase activity, and stimulated murine peritoneal macrophages to produce high levels of TNF-α and nitric oxide. Considering the immunomodulatory potential of glycan-binding proteins, we also investigated whether prophylactic administration of recombinant paracoccin affected the course of experimental paracoccidioidomycosis in mice. In comparison to animals injected with vehicle (controls), mice treated with recombinant paracoccin displayed lower pulmonary fungal burdens and reduced pulmonary granulomas. These protective effects were associated with augmented pulmonary levels of IL-12 and IFN-γ. We also observed that injection of paracoccin three days before challenge was the most efficient administration protocol, as the induced Th1 immunity was balanced by high levels of pulmonary IL-10, which may prevent the tissue damage caused by exacerbated inflammation. The results indicated that paracoccin is the protein encoded by PADG-3347, and we propose that this gene and homologous proteins in other P. brasiliensis strains be called paracoccin. We also concluded that recombinant paracoccin confers resistance to murine P. brasiliensis infection by exerting immunomodulatory effects.

The role of macrophages and dendritic cells in the initiation of inflammation in IBD

In the healthy gastrointestinal tract, homeostasis is an active process that requires a careful balance of host responses to the enteric luminal contents. Intestinal macrophages and dendritic cells (DCs) comprise a unique group of tissue immune cells that are ideally situated at the interface of the host and the enteric luminal environment to appropriately respond to microbes and ingested stimuli. However, intrinsic defects in macrophage and DC function contribute to the pathogenesis of inflammatory bowel diseases, as highlighted by recent genome-wide association studies. Gastrointestinal macrophages and DCs participate in inflammatory bowel disease development through inappropriate responses to enteric microbial stimuli, inefficient clearance of microbes from host tissues, and impaired transition from appropriate proinflammatory responses to anti-inflammatory responses that promote resolution. By understanding how intestinal macrophages and DCs initiate chronic inflammation, new pathogenesis-based therapeutic strategies to treat human inflammatory bowel diseases will be elucidated.

Suppression of SERPINA1-albumin complex formation by galectin-3 overexpression leads to paracrine growth promotion of chronic myelogenous leukemia cells

Galectin-3 is induced in chronic myelogenous leukemia (CML) cells by co-culture with bone marrow stromal cells, making paracrine growth promotion of CML cells in conditioned medium (CM) from galectin-3 overexpressing CML cells more potent. We used gel filtration chromatography to demonstrate that the bovine SERPINA1-fetal bovine serum albumin (BSA) complex was specifically suppressed in CM from galectin-3 overexpressing cells. The SERPINA1-BSA complex as well as human plasma SERPINA1 inhibited the growth of CML cells, while exogenous galectin-3 partly offset this effect. These findings suggest that galectin-3 overexpression promotes paracrine growth of CML cells by interfering with the action of the growth inhibitory SERPINA1-albumin complex.

Galectin-3 plays an important role in protection against disseminated candidiasis

Recent in vitro studies have implicated galectin-3 as an important receptor in host recognition and response to specific Candida species; however, its role in protection against disseminated candidiasis in vivo has not been evaluated. This study investigated the importance of galectin-3 in host defense against systemic infection with the highly virulent species Candida albicans, and the less virulent species, C. parapsilosis. Mice deficient in galectin-3 (gal3-/-) were more susceptible to infection than wild-type (WT) mice. When infected with C. albicans, gal3-/- mice died significantly faster and exhibited a trend towards increased fungal burden and increased abscess formation in infected brains compared to WT mice. When infected with C. parapsilosis, gal3-/- mice had significantly higher renal fungal burdens and abscess formation compared to WT mice. To evaluate whether galectin-3 may contribute to susceptibility to candidiasis in human infants, galectin-3 levels in sera of newborn infants, a patient population uniquely susceptible to infections with both C. albicans and C. parapsilosis, were compared to serum galectin-3 levels of adults. Galectin-3 levels were significantly lower in newborn infant sera compared to adult sera. These data indicate that galectin-3 plays an important role in a murine model of disseminated candidiasis and suggest a potential mechanism of neonatal susceptibility to these infections.

Galectin-3 negatively regulates dendritic cell production of IL-23/IL-17-axis cytokines in infection by Histoplasma capsulatum

Galectin-3 (gal3) is known for its immunoregulatory functions in infectious, autoimmune, and inflammatory diseases. However, little is known about its regulatory role in the host's IL-17A response to infection. Using a mouse model of histoplasmosis in which both Th1 and Th17 responses contribute to fungal clearance, we investigated how gal3 regulates IL-17A responses. Our study showed that Histoplasma infection induced gal3(-/-) dendritic cells to produce significantly higher levels of IL-23, TGF-β1, and IL-1β than did gal3(+/+) cells. Infected by the same inoculum of Histoplasma, gal3(-/-) mice had lower fungal burden and produced higher levels of IL-23/IL-17-axis cytokines and lower levels of IL-12 and IFN-γ. Additionally, there was an increase in Th17 cells and a reduction in Th1 cells in infected gal3(-/-) mice. In vitro Th1/Th17-skewing experiments excluded the intrinsic effect of gal3 on Th cell differentiation. Although neutrophils from both gal3(+/+) and gal3(-/-) mice produced IL-17A upon IL-23 stimulation, their contribution to IL-17A production was greater in gal3(-/-) mice than in gal3(+/+) mice. Compared with gal3(+/+) dendritic cells, adoptive transfer of gal3(-/-) dendritic cells resulted in production of significantly higher levels of IL-17-axis cytokines and reduced fungal burden. It appears that reduced fungal burden and preferential IL-17A response in gal3(-/-) mice by both Th17 cells and neutrophils were the result of preferential production of IL-23/IL-17-axis cytokines by dendritic cells. Our study showed that gal3 negatively regulates IL-17A responses through inhibition of IL-23/IL-17-axis cytokine production by dendritic cells.

Lack of galectin-3 speeds Wallerian degeneration by altering TLR and pro-inflammatory cytokine expressions in injured sciatic nerve

Wallerian degeneration (WD) comprises a series of events that includes activation of non-neuronal cells and recruitment of immune cells, creating an inflammatory milieu that leads to extensive nerve fragmentation and subsequent clearance of the myelin debris, both of which are necessary prerequisites for effective nerve regeneration. Previously, we documented accelerated axon regeneration in animals lacking galectin-3 (Gal-3), a molecule associated with myelin clearance. To clarify the mechanisms underlying this enhanced regeneration, we focus here on the early steps of WD following sciatic nerve crush in Gal-3(-/-) mice. Using an in vivo model of nerve degeneration, we observed that removal of myelin debris is more efficient in Gal-3(-/-) than in wild-type (WT) mice; we next used an in vitro phagocytosis assay to document that the phagocytic potential of macrophages and Schwann cells was enhanced in the Gal-3(-/-) mice. Moreover, both RNA and protein levels for the pro-inflammatory cytokines IL-1β and TNF-α, as well as for Toll-like receptor (TLR)-2 and -4, show robust increases in injured nerves from Gal-3(-/-) mice compared to those from WT mice. Collectively, these data indicate that the lack of Gal-3 results in an augmented inflammatory profile that involves the TLR-cytokine pathway, and increases the phagocytic capacity of Schwann cells and macrophages, which ultimately contributes to speeding the course of WD.

The role of galectin-3 in phagocytosis of Candida albicans and Candida parapsilosis by human neutrophils

Candida albicans causes the majority of invasive candidiasis in immunocompromised adults while Candida parapsilosis is a leading cause of neonatal candidiasis. While much work has focused on how the immune system recognizes and responds to C. albicans, less is known about host interaction with C. parapsilosis. This study investigates the human neutrophil phagocytic response to these species. Neutrophils underwent phagocytosis of C. parapsilosis yeast and C. albicans hyphae much more efficiently than C. albicans yeast. Treatment of neutrophils with a galectin-3 (gal3) blocking antibody inhibited phagocytosis of C. parapsilosis yeast and C. albicans hyphae, but not C. albicans yeast. The majority of neutrophil gal3 was expressed intracellularly and was secreted from neutrophils after treatment with C. parapsilosis mannan. When neutrophils were treated with exogenous gal3, phagocytosis of both C. albicans and C. parapsilosis yeast increased. Exposure of neutrophils to C. parapsilosis yeast increased phagocytosis of C. albicans yeast and was inhibited by gal3 blocking antibody. Taken together, these data indicate that gal3 secreted from neutrophils may act as a pro-inflammatory autocrine/paracrine signal in neutrophil phagocytosis and suggest that gal3 has a unique role in neutrophil response to C. parapsilosis yeast and C. albicans hyphae distinct from C. albicans yeast.

Galectin-3 regulates the innate immune response of human monocytes

Galectin-3 is a β-galactoside-binding lectin widely expressed on epithelial and hematopoietic cells, and its expression is frequently associated with a poor prognosis in cancer. Because it has not been well-studied in human infectious disease, we examined galectin-3 expression in mycobacterial infection by studying leprosy, an intracellular infection caused by Mycobacterium leprae. Galectin-3 was highly expressed on macrophages in lesions of patients with the clinically progressive lepromatous form of leprosy; in contrast, galectin-3 was almost undetectable in self-limited tuberculoid lesions. We investigated the potential function of galectin-3 in cell-mediated immunity using peripheral blood monocytes. Galectin-3 enhanced monocyte interleukin 10 production to a TLR2/1 ligand, whereas interleukin 12p40 secretion was unaffected. Furthermore, galectin-3 diminished monocyte to dendritic cell differentiation and T-cell antigen presentation. These data demonstrate an association of galectin-3 with unfavorable host response in leprosy and a potential mechanism for impaired host defense in humans.

Galectin-3 is essential for reactive oxygen species production by peritoneal neutrophils from mice infected with a virulent strain ofToxoplasma gondii

Toxoplasma gondiistimulates a potent pro-inflammatory response and neutrophils are involved in early infection. Galectin-3 (Gal-3) is an endogenous modulator of inflammatory processes and anti-infective agents, but its interaction with neutrophils inT. gondiiinfection is still unclear. Here, we evaluated the role of Gal-3 in peritoneal inflammation, reactive oxygen species (ROS) production by neutrophils and survival, afterin vivo T. gondiiinfection with virulent RH strain, using Gal-3 deficient and wild type mice. Animals were inoculated with thioglycollate or tachyzoites, and peritoneal cells were harvested for analysis of the influx of leukocytes. Neutrophils were isolated from peritoneal exudates from infected mice and stimulated with phorbol myristate acetate (PMA) to evaluate ROS production by luminol-dependent chemiluminescence assay. Our results showed that: (1) Gal-3 upregulates peritoneal inflammation, with enhanced recruitment of neutrophils and lymphocytes after thioglycollate stimulation, but does not influence the enhanced neutrophil influx after earlyT. gondiiinfection; (2) Gal-3 upregulates ROS generation by inflammatory peritoneal neutrophils from infected mice, but downregulates its production in non-infected mice and (3) Gal-3 does not influence the survival of mice after infection with the virulentT. gondiistrain. In conclusion, Gal-3 is essential for ROS generation by neutrophils in the initial acute phase ofT. gondiiinfection and this phenomenon may constitute an attempt to control parasite growth duringin vivoinfection with theT. gondiivirulent strain.

The roles of Galectin-3 in autoimmunity and tumor progression

Galectin-3, a unique chimera-type member of the β-galactoside-binding soluble lectin family, is widely expressed in numerous cells. Here, we discuss the role of Galectin-3 in T-cell-mediated inflammatory (auto) immunity and tumor rejection by using Galectin-3-deficient mice and four disease models of human pathology: experimental autoimmune encephalomyelitis (EAE), Con-A-induced hepatitis, multiple low-dose streptozotocin-induced diabetes (MLD-STZ diabetes) and metastatic melanoma. We present evidence which suggest that Galectin-3 plays an important pro-inflammatory role in Con-A-induced hepatitis by promoting the activation of T lymphocytes, NKT cells and DCs, cytokine secretion, prevention of M2 macrophage polarization and apoptosis of mononuclear cells, and it leads to severe liver injury. In addition, experiments in Galectin-3-"knock-out" mice indicate that Galectin-3 is also involved in immune-mediated β-cell damage and is required for diabetogenesis in MLD-STZ model by promoting the expression of IFN-gamma, TNF-alpha, IL-17 and iNOS in immune and accessory effector cells. Next, our data demonstrated that Galectin-3 plays an important disease-exacerbating role in EAE through its multifunctional roles in preventing cell apoptosis and increasing IL-17 and IFN-gamma synthesis, but decreasing IL-10 production. Finally, based on our findings, we postulated that expression of Galectin-3 in the host may also facilitate melanoma metastasis by affecting tumor cell adhesion and modulating anti-melanoma immune response, in particular innate antitumor immunity. Taken together, we discuss the evidence of pro-inflammatory and antitumor activities of Galectin-3 and suggest that Galectin-3 may be an important therapeutic target.

ArtinM offers new perspectives in the development of antifungal therapy

The thermally dimorphic fungus Paracoccidioides brasiliensis is the causative agent of paracoccidioidomycosis (PCM), the most frequent systemic mycosis that affects the rural populations in Latin America. Despite significant developments in antifungal chemotherapy, its efficacy remains limited since drug therapy is prolonged and associated with toxic side effects and relapses. In response to these challenges, it is now recognized that several aspects of antifungal immunity can be modulated to better deal with fungal infections. A common idea for halting fungal infections has been the need to activate a cell-based, pro-inflammatory Th1 immune response to improve the fungal elimination. ArtinM, a D-mannose binding lectin from Artocarpus heterophyllus, has the property of modulating immunity against several intracellular pathogens. Here, we review the immunomodulatory activity of ArtinM during experimental PCM in mice. Both prophylactic and therapeutic protocols of ArtinM administration promotes a Th1 immune response balanced by IL-10, which outstandingly reduces the fungal load in organs of the treated mice while maintaining a controlled inflammation at the site of infection. A carbohydrate recognition-based interaction of ArtinM with Toll-like receptor 2 (TLR2) accounts for initiating the immunomodulatory effect of the lectin. The precise identification of the TLR2 N-glycan(s) targeted by ArtinM may support novel basis for the development of antifungal therapy.

Effects of novel vaccine/adjuvant complexes on the protective immunity against Eimeria acervulina and transcriptome profiles

SUMMARY. This study investigated the ability of two novel adjuvant formulations, QCDC (Quil A/cholesterol/DDA/ Carbopol) and QCDCR (QCDC/Bay R1005), in combination with a recombinant profilin vaccine, to modulate host protective immunity and to alter gene expression during experimental avian coccidiosis. Vaccination with profilin plus QCDCR significantly reduced the severity of intestinal lesions and increased mitogen-induced lymphocyte proliferation in infected chickens compared with immunization with profilin alone or profilin plus QCDC. Immunization with profilin plus QCDC or profilin plus QCDCR increased body weight gain but had no effect on fecal oocyst shedding of chickens infected with Eimeria acervulina compared with birds vaccinated with profilin alone. The results of global gene expression analysis revealed that, compared with PBS controls, (a) chickens vaccinated with profilin alone had 71 up-regulated and 56 down-regulated mRNA transcripts, (b) chickens immunized with profilin plus QCDC had 198 up-regulated and 247 down-regulated mRNAs, and (c) birds immunized with profilin plus QCDCR had 210 up-regulated and 267 down-regulated mRNAs. Compared with birds vaccinated with profilin alone, (a) chickens given profilin plus QCDC had 60 up-regulated and 104 down-regulated transcripts and (b) chickens immunized with profilin plus QCDCR had 103 up-regulated and 130 down-regulated mRNAs. Finally, chickens vaccinated with profilin plus QCDCR had 193 up-regulated and 204 down-regulated transcripts compared with birds given profilin plus QCDC. Biological function and network analysis revealed that the majority of altered transcripts were encoded by immune-related genes.

Innate and adaptive antifungal immune responses: partners on an equal footing

Adaptive immunity has long been regarded as the major player in protection against most fungal infections. Mounting evidence suggest however, that both innate and adaptive responses intricately collaborate to produce effective antifungal protection. Dendritic cells (DCs) play an important role in initiating and orchestrating antifungal immunity; neutrophils, macrophages and other phagocytes also participate in recognising and eliminating fungal pathogens. Adaptive immunity provides a wide range of effector and regulatory responses against fungal infections. Th1 responses protect against most forms of mycoses but they associate with significant inflammation and limited pathogen persistence. By contrast, Th2 responses enhance persistence of and tolerance to fungal infections thus permitting the generation of long-lasting immunological memory. Although the role of Th17 cytokines in fungal immunity is not fully understood, they can enhance proinflammatory or anti-inflammatory responses or play a regulatory role in fungal immunity all depending on the pathogen, site/phase of infection and host immunostatus. T regulatory cells balance the activities of various Th cell subsets thereby permitting inflammation and protection on the one hand and allowing for tolerance and memory on the other. Here, recent developments in fungal immunity research are reviewed as means of tracing the emergence of a refined paradigm where innate and adaptive responses are viewed in the same light.

Galectin-3 exerts cytokine-like regulatory actions through the JAK-STAT pathway

Galectin-3, a β-galactoside-binding lectin, has been proposed to have multifaceted functions in various pathophysiological conditions. However, the characteristics of galectin-3 and its molecular mechanisms of action are still largely unknown. In this study, we show that galectin-3 exerts cytokine-like regulatory actions in rat and mouse brain-resident immune cells. Both the expression of galectin-3 and its secretion into the extracellular compartment were significantly enhanced in glia under IFN-γ-stimulated, inflamed conditions. After exposure to galectin-3, glial cells produced high levels of proinflammatory mediators and exhibited activated properties. Notably, within minutes after exposure to galectin-3, JAK2 and STAT1, STAT3, and STAT5 showed considerable enhancement of tyrosine phosphorylation; thereafter, downstream events of STAT signaling were also significantly enhanced. Treatment of the cells with pharmacological inhibitors of JAK2 reduced the galectin-3-stimulated increases of inflammatory mediators. Using IFN-γ receptor 1-deficient mice, we further found that IFN-γR 1 might be required for galectin-3-dependent activation of the JAK-STAT cascade. However, galectin-3 significantly induced phosphorylation of STATs in glial cells from IFN-γ-deficient mice, suggesting that IFN-γ does not mediate activation of STATs. Collectively, our findings suggest that galectin-3 acts as an endogenous danger signaling molecule under pathological conditions in the brain, providing a potential explanation for the molecular basis of galectin-3-associated pathological events.

Lack of galectin-3 alleviates trypanosomiasis-associated anemia of inflammation

A typical pathological feature associated with experimental African trypanosomiasis (Trypanosoma brucei infection in mice) is anemia of chronic disease (ACD), which is due to a sustained type 1 cytokine-mediated inflammation and hyperactivation of M1 macrophages. Galectin-3 (Gal-3) was amply documented to contribute to the onset and persistence of type 1 inflammatory responses and we herein document that this protein is strongly upregulated during T. brucei infection. We evaluated the involvement of Gal-3 in trypanosomiasis-associated anemia using galectin-3 deficient (Gal3(-/-)) mice. T. brucei infected Gal3(-/-) mice manifested significant lower levels of anemia during infection and survived twice as long as wild type mice. Moreover, such mice showed increased levels of serum IL-10 and reduced liver pathology (as evidenced by lower AST/ALT levels). In addition, there was also an increase in gene expression of iron export genes and a reduced expression of genes, which are associated with accumulation of cellular iron. Our data indicate that Gal-3 is involved in the development of inflammation-associated anemia during African trypanosomiasis, possibly due to a disturbed iron metabolism that in turn may also lead to liver malfunction.

Galectin-3 plays a modulatory role in the life span and activation of murine neutrophils during early Toxoplasma gondii infection

Galectins are beta-galactoside-binding lectins involved in several biological processes and galectin-3 (Gal-3) is related to modulation of immune and inflammatory responses. This study aimed to evaluate the role of Gal-3 in the life span and biological functions of murine neutrophils during in vitro infection by virulent Toxoplasma gondii RH strain. Inflammatory peritoneal neutrophils (Nphi) from C57BL/6 wild-type (WT) and Gal-3 knockout (KO) mice were cultured in the presence or absence of parasites and analyzed for phosphatidylserine (PS) exposure and cell death using Annexin-V and propidium iodide staining, and cell viability by MTT assay. Cell toxicities determined by lactate dehydrogenase (LDH), degranulation by lysozyme release, and cytokine production were measured in Nphi culture supernatants. Phorbol myristate acetate (PMA)- or zymosan-dependent reactive oxygen species (ROS) were measured in Nphi cultures. Our results demonstrated that Gal-3 is involved in the increase of the viable Nphi number and the decrease of PS exposure and cell death following T. gondii infection. We also observed that Gal-3 downmodulates T. gondii-induced Nphi toxicity as well as Nphi degranulation regardless of infection. Furthermore, Gal-3 expression by Nphi was associated with increased levels of IL-10 in the beginning and decreased levels of TNF-alpha later on, regardless of parasite infection, as well as with decreased levels of IL-6 and increased IL-12 levels, following early parasite infection. Our results also showed that Gal-3 suppresses PMA- but not zymosan-induced ROS generation in Nphi following T. gondii infection. In conclusion, Gal-3 plays an important modulatory role by interfering in Nphi life span and activation during early T. gondii infection.