Examination of testicular lumicrine regulation of activins and immunoregulatory genes in the epididymal caput.

BACKGROUND: Immunoregulatory genes encoding activin A (Inhba) and B (Inhbb), and indolamine 2,3-dioxygenase-1 (Ido1) are highly expressed in the murine caput epididymidis, which also has a network of intraepithelial mononuclear phagocytes. This environment is postulated to promote immunological tolerance to epididymal sperm. The factors regulating the immunoregulatory agents in the epididymal caput are poorly understood. OBJECTIVES: This study aimed to investigate the potential role of testicular lumicrine factors in regulating activin and other immune-related genes in the caput epididymidis. MATERIALS AND METHODS: The efferent ducts in adult C57/Bl6 mice were exposed and ligated bilaterally. Serum and tissues were collected seven days later. Animals with bilateral sham ligation and animals with no ligations (collectively referred to as the "intact" group) were used as controls. RESULTS: Pressure-induced seminiferous epithelial damage due to intratubular fluid accumulation was observed in all ligated testes. Testicular inhibin was significantly increased and testosterone was elevated in some animals following bilateral ligation, but serum testosterone, serum LH, and serum inhibin were normal. Ligation caused epithelial regression in the initial segment, with similar but less severe effects in other caput segments. Activin A staining by immunohistochemistry in the epithelium was reduced in bilateral ligation, particularly in the initial segment, with moderately reduced staining intensity in the rest of the caput. Inhba expression within the caput was not significantly affected by bilateral ligation, but Inhbb was reduced by more than 60%. Transcripts encoding the macrophage-specific receptor Cx3cr1 were significantly reduced following bilateral ligation, but other immune cell markers, Ido1, and inflammatory genes were unaffected. CONCLUSION: These data indicate that testicular lumicrine secretion regulates several genes that are preferentially expressed in the initial segment, but has marginal effects on genes such as those encoding activin A and IDO1, which are expressed more widely in the caput.

Inhibition of Activin A suppressed tumor necrosis factor-α secretion and improved histopathological conditions in malarial mice.

Malaria infection still remains as one of the most prominent parasitic diseases afflicting mankind in tropical and subtropical regions. The severity of malaria infection has often been associated to exuberant host immune inflammatory responses that could possibly lead to severe immunopathological conditions and subsequent death of host tissues. Activin A is a protein belonging to the transforming growth factor-beta (TGF-ß) family that regulates multiple physiological processes and pathological-associated diseases. The biological roles of activin A have been associated with manipulation of inflammation-related processes and modulation of host immune responses. This implies that activin A protein could play a role in malaria pathogenesis since malaria infection has been closely linked to severe immune responses leading to death, However, the actual in vivo role of activin A in malaria infection remains elusive. Hence, this study was undertaken to investigate the involvement of activin A in malaria infection as well as to assess the modulating effects of activin A on the cytokine releases (TNF-α, IFN-γ and IL-10) and histopathological changes in major affected organs (kidney, liver, lung, brain and spleen) in malarial mice infected with Plasmodium berghei ANKA. Our results showed that the concentrations of plasma activin A were significantly increased in malarial mice throughout the study periods. Also. the systemic activin A level was positively correlated with malaria parasitemia. This indicates that activin A could play a role in malaria pathogenesis and malaria parasitemia development. Plasma TNF-α, IFN-γ and IL-10 cytokine levels were significantly increased in malarial mice at day-5 post infection, suggesting that these cytokines attributed to severe malaria pathogenesis. Histopathological features such as sequestration of parasitized red blood cells (pRBCs) and hemozoin formation were amongst the most common pathological conditions observed in tissues of major affected organs (kidney, liver, lung, brain and spleen) in malarial mice. Neutralization of activin A production via recombinant mouse activin RIIA Fc chimera (rmActivin RIIA Fc chimera) had significantly reduced the parasitemia levels in malarial mice. The release of TNF-α cytokine was significantly reduced as well as the sequestration of parasitized pRBCs and hemozoin formation in major affected organs in malarial mice were also alleviated following inhibition of activin A production. Overall, this preliminary study suggests that activin A could play an immune modulation role in malaria pathogenesis through modulation of TNF-α release that benefits host from severe pathological destructions provoked by intensified inflammatory responses. Further studies are warranted to elucidate the precise mechanism of immune modulation mediated by activin A and its associated immune-modulation mediators in regulating the inflammatory responses elicited during the course of malaria infection.

CD28 is expressed by macrophages with anti-inflammatory potential and limits their T-cell activating capacity.

CD28 expression is generally considered to be T lymphocyte specific. We have previously shown CD28 mRNA expression in M-CSF-dependent anti-inflammatory monocyte-derived macrophages (M-MØ), and now demonstrate that CD28 cell surface expression is higher in M-MØ than in GM-CSF-dependent macrophages, and that macrophage CD28 expression is regulated by MAFB and activin A. In vivo, CD28 was found in tumor-associated macrophages and, to a lower extent, in pro-inflammatory synovial fluid macrophages from rheumatoid arthritis patients. Analysis of mouse macrophages confirmed Cd28 expression in bone-marrow derived M-MØ. Indeed, anti-CD28 antibodies triggered ERK1/2 phosphorylation in mouse M-MØ. At the functional level, Cd28KO M-MØ exhibited a significantly higher capacity to activate the OVA-specific proliferation of OT-II CD4+ T cells than WT M-MØ, as well as enhanced LPS-induced IL-6 production. Besides, the Cd28KO M-MØ transcriptome was significantly different from WT M-MØ regarding the expression IFN response, inflammatory response, and TGF-ß signaling related gene sets. Therefore, defective CD28 expression in mouse macrophages associates to changes in gene expression profile, what might contribute to the altered functionality displayed by Cd28KO M-MØ. Thus, CD28 expression appears as a hallmark of anti-inflammatory macrophages and might be a target for immunotherapy.

Harnessing Activin A Adjuvanticity to Promote Antibody Responses to BG505 HIV Envelope Trimers.

T follicular helper (TFH) cells are powerful regulators of affinity matured long-lived plasma cells. Eliciting protective, long-lasting antibody responses to achieve persistent immunity is the goal of most successful vaccines. Thus, there is potential in manipulating TFH cell responses. Herein, we describe an HIV vaccine development approach exploiting the cytokine activin A to improve antibody responses against recombinant HIV Envelope (Env) trimers in non-human primates. Administration of activin A improved the magnitude of Env-specific antibodies over time and promoted a significant increase in Env-specific plasma cells in the bone marrow. The boost in antibody responses was associated with reduced frequencies of T follicular regulatory (TFR) cells and increased germinal center T follicular helper (GC-TFH) to TFR cell ratios. Overall, these findings suggest that adjuvants inducing activin A production could potentially be incorporated in future rational design vaccine strategies aimed at improving germinal centers, long-lived plasma cells, and sustained antibody responses.

Expansion of Host Regulatory T Cells by Secreted Products of the Tapeworm Echinococcus multilocularis.

Background: Alveolar echinococcosis (AE), caused by the metacestode larval stage of the fox-tapeworm Echinococcus multilocularis, is a chronic zoonosis associated with significant modulation of the host immune response. A role of regulatory T-cells (Treg) in generating an immunosuppressive environment around the metacestode during chronic disease has been reported, but the molecular mechanisms of Treg induction by E. multilocularis, particularly parasite immunoregulatory factors involved, remain elusive so far. Methodology/Principal Findings: We herein demonstrate that excretory/secretory (E/S) products of the E. multilocularis metacestode promote the formation of Foxp3+ Treg from CD4+ T-cells in vitro in a TGF-ß-dependent manner, given that this effect was abrogated by treatment with antibody to mammalian TGF-ß. We also show that host T-cells secrete elevated levels of the immunosuppressive cytokine IL-10 in response to metacestode E/S products. Within the E/S fraction of the metacestode we identified an E. multilocularis activin A homolog (EmACT) that displays significant similarities to mammalian Transforming Growth Factor-ß (TGF-ß/activin subfamily members. EmACT obtained from heterologous expression failed to directly induce Treg expansion from naïve T cells but required addition of recombinant host TGF-ß to promote CD4+ Foxp3+ Treg conversion in vitro. Furthermore, like in the case of metacestode E/S products, EmACT-treated CD4+ T-cells secreted higher levels of IL-10. These observations suggest a contribution of EmACT to in vitro expansion of Foxp3+ Treg by the E. multilocularis metacestode. Using infection experiments we show that intraperitoneally injected metacestode tissue expands host Foxp3+ Treg, confirming the expansion of this cell type in vivo during parasite establishment. Conclusion/Significance: In conclusion, we herein demonstrate that E. multilocularis larvae secrete factors that induce the secretion of IL-10 by T-cells and contribute to the expansion of TGF-b-driven Foxp3+ Treg, a cell type that has been reported crucial for generating a tolerogenic environment to support parasite establishment and proliferation. Among the E/S factors of the parasite we identified a factor with structural and functional homologies to mammalian activin A which might play an important role in these activities.

Activin A Modulates Inflammation in Acute Pancreatitis and Strongly Predicts Severe Disease Independent of Body Mass Index.

INTRODUCTION: Acute pancreatitis (AP) is a healthcare challenge with considerable mortality. Treatment is limited to supportive care, highlighting the need to investigate disease drivers and prognostic markers. Activin A is an established mediator of inflammatory responses, and its serum levels correlate with AP severity. We hypothesized that activin A is independent of body mass index (BMI) and is a targetable promoter of the AP inflammatory response. METHODS: We assessed whether BMI and serum activin A levels are independent markers to determine disease severity in a cohort of patients with AP. To evaluate activin A inhibition as a therapeutic, we used a cerulein-induced murine model of AP and treated mice with activin A-specific neutralizing antibody or immunoglobulin G control, both before and during the development of AP. We measured the production and release of activin A by pancreas and macrophage cell lines and observed the activation of macrophages after activin A treatment. RESULTS: BMI and activin A independently predicted severe AP in patients. Inhibiting activin A in AP mice reduced disease severity and local immune cell infiltration. Inflammatory stimulation led to activin A production and release by pancreas cells but not by macrophages. Macrophages were activated by activin A, suggesting activin A might promote inflammation in the pancreas in response to injury. DISCUSSION: Activin A provides a promising therapeutic target to interrupt the cycle of inflammation and tissue damage in AP progression. Moreover, assessing activin A and BMI in patients on hospital admission could provide important predictive measures for screening patients likely to develop severe disease.

Activin-A in the regulation of immunity in health and disease.

The TGF-ß superfamily of cytokines plays pivotal roles in the regulation of immune responses protecting against or contributing to diseases, such as, allergy, autoimmunity and cancer. Activin-A, a member of the TGF-ß superfamily, was initially identified as an inducer of follicle-stimulating hormone secretion. Extensive research over the past decades illuminated fundamental roles for activin-A in essential biologic processes, including embryonic development, stem cell maintenance and differentiation, haematopoiesis, cell proliferation and tissue fibrosis. Activin-A signals through two type I and two type II receptors which, upon ligand binding, activate their kinase activity, phosphorylate the SMAD2 and 3 intracellular signaling mediators that form a complex with SMAD4, translocate to the nucleus and activate or silence gene expression. Most immune cell types, including macrophages, dendritic cells (DCs), T and B lymphocytes and natural killer cells have the capacity to produce and respond to activin-A, although not in a similar manner. In innate immune cells, including macrophages, DCs and neutrophils, activin-A exerts a broad range of pro- or anti-inflammatory functions depending on the cell maturation and activation status and the spatiotemporal context. Activin-A also controls the differentiation and effector functions of Th cell subsets, including Th9 cells, TFH cells, Tr1 Treg cells and Foxp3+ Treg cells. Moreover, activin-A affects B cell responses, enhancing mucosal IgA secretion and inhibiting pathogenic autoantibody production. Interestingly, an array of preclinical and clinical studies has highlighted crucial functions of activin-A in the initiation, propagation and resolution of human diseases, including autoimmune diseases, such as, systemic lupus erythematosus, rheumatoid arthritis and pulmonary alveolar proteinosis, in allergic disorders, including allergic asthma and atopic dermatitis, in cancer and in microbial infections. Here, we provide an overview of the biology of activin-A and its signaling pathways, summarize recent studies pertinent to the role of activin-A in the modulation of inflammation and immunity, and discuss the potential of targeting activin-A as a novel therapeutic approach for the control of inflammatory diseases.

The Activin-like ligand Dawdle regulates innate immune responses through modulating NF-κB signaling in mud crab Scylla paramamosain.

Activins, members of transforming growth factor ß (TGF-ß) superfamily, are pleiotropic cytokines with critical roles in mediating cell proliferation, differentiation, homeostasis, apoptosis and immune response. However, the structural characteristics and specific functions of Activins remain largely unknown in invertebrates. In the present study, an Activin-like ligand Dawdle (Daw) was firstly identified and characterized from mud crab Scylla paramamosain. The obtained cDNA sequence of SpDaw was 2, 196 bp long with a 1, 149 bp open reading fame, which encoded a putative protein of 382 amino acids. The putative SpDaw protein contained a signal peptide, a TGF-ß propeptide region and a TGF-ß domain. Real-time PCR analysis demonstrated that SpDaw was predominantly expressed at early embryonic development stage and premolt stages, implying its participation in development and growth. Furthermore, SpDaw responded to both Vibro alginolyticus and Poly (I:C) challenges, suggesting the involvement of SpDaw in innate immune responses. Knockdown of SpDaw in vivo dramatically increased the expressions of NF-κB signaling genes and anti-lipopolysaccharide factor (ALF) genes, and the bacteria clearance efficiency was also markedly enhanced in SpDaw-silenced crabs. Moreover, the in vitro experiment further demonstrated that recombinant SpDaw protein could block the increased transcription of IKKs, NF-κBs and ALFs induced by pathogen challenges. Taken together, these results indicated that SpDaw not only participated in development and growth processes but also played an immune-regulatory role in crabs' innate immunity, which may pave the way for a better understanding of TGF-ß superfamily members in crustacean species.

Inhibitory Antibodies against Activin A and TGF-ß Reduce Self-Supported, but Not Soluble Factors-Induced Growth of Human Pulmonary Arterial Vascular Smooth Muscle Cells in Pulmonary Arterial Hypertension.

Increased growth and proliferation of distal pulmonary artery vascular smooth muscle cells (PAVSMC) is an important pathological component of pulmonary arterial hypertension (PAH). Transforming Growth Factor-ß (TGF-ß) superfamily plays a critical role in PAH, but relative impacts of self-secreted Activin A, Gremlin1, and TGF-ß on PAH PAVSMC growth and proliferation are not studied. Here we report that hyper-proliferative human PAH PAVSMC have elevated secretion of TGF-ß1 and, to a lesser extent, Activin A, but not Gremlin 1, and significantly reduced Ser465/467-Smad2 and Ser423/425-Smad3 phosphorylation compared to controls. Media, conditioned by PAH PAVSMC, markedly increased Ser465/467-Smad2, Ser423/425-Smad3, and Ser463/465-Smad1/5 phosphorylation, up-regulated Akt, ERK1/2, and p38 MAPK, and induced significant proliferation of non-diseased PAVSMC. Inhibitory anti-Activin A antibody reduced PAH PAVSMC growth without affecting canonical (Smads) or non-canonical (Akt, ERK1/2, p38 MAPK) effectors. Inhibitory anti-TGF-ß antibody significantly reduced P-Smad3, P-ERK1/2 and proliferation of PAH PAVSMC, while anti-Gremlin 1 had no anti-proliferative effect. PDGF-BB diminished inhibitory effects of anti-Activin A and anti-TGF-ß antibodies. None of the antibodies affected growth and proliferation of non-diseased PAVSMC induced by PAH PAVSMC-secreted factors. Together, these data demonstrate that human PAH PAVSMC have secretory, proliferative phenotype that could be targeted by anti-Activin A and anti-TGF-ß antibodies; potential cross-talk with PDGF-BB should be considered while developing therapeutic interventions.

Activin-A Is a Pro-Inflammatory Regulator in Type-2-Driven Upper Airway Disease.

BACKGROUND: Allergic upper airway disease involves pro-inflammatory type-2 cytokines such as IL-5 and regulatory tissue repair mediators, in particular transforming growth factor (TGF)-ß1. The TGF-ß-superfamily member activin-A displays multiple biological functions and shares certain signalling pathways with TGF-ß1. We aimed to examine the coregulation of mucosal activin-A and TGF-ß1 in acute allergic and chronic Th2-driven upper airway disease. METHODS: We investigated mucosal cytokine expression profiles and kinetics using RT-PCR after nasal allergen challenges in patients with seasonal allergic rhinitis. Furthermore, we analysed mucosal specimens from patients with chronic upper airway disease with nasal polyps using ELISPOTs and confocal microscopy. In addition, we stimulated nasal mucosa ex vivo from patients with nasal polyps as well as primary nasal cell cultures from healthy donors. RESULTS: Mucosal activin-A expression revealed increasing correlation with IL-5 and TGF-ß1 at 0.25, 6, and 24 h, respectively, and was significantly upregulated at 6 h after allergen challenge. The correlated expression was found to be more pronounced in chronic disease with nasal polyps, showing substantially (48-fold) increased activin-A-producing cells in nasal polyps by ELISPOT, while submucosal downstream signalling as determined by confocal microscopy was decreased. Ex vivo stimulations of nasal tissue suggested that activin-A and TGF-ß1 mutually regulate each other's expression at the mRNA level and, when combined, enhance IL-5 expression. CONCLUSION: Activin-A in allergic upper airway disease acts as a pro-inflammatory mediator and TGF-ß1 modifier. Our data in the upper airways oppose the view of potentially anti-inflammatory properties in contrast to lymphatic compartments.

Regulatory T cells are required for normal and activin-promoted wound repair in mice.

Healing of skin wounds is orchestrated by various types of immune cells, but little is known about the role of FoxP3+ regulatory T cells (Tregs) in this process. Here, we determined if Tregs are important for wound healing in normal mice and if they contribute to the accelerated healing of mice overexpressing the growth and differentiation factor activin. Diphtheria toxin induced Treg depletion prior to injury caused impaired healing characterized by delayed reepithelialization, reduced wound contraction, and impaired vessel maturation. The accelerated wound repair of activin-transgenic mice was also abrogated. Mechanistically, we found a strong increase in IL-4 levels combined with overrepresentation of T-bet+ and GATA-3+ αß T cells in Treg-depleted 7-day wounds. In addition, numbers of IFN-γ- or IL-17A-producing CD4+ and CD4- T cells were elevated. These results demonstrate that Treg depletion in wounds facilitates the expansion of an αß T-cell population with features of Th1 and Th2 cells, and suggest that concomitant changes in the cytokine milieu disturb the healing process.

Dendritic cells conditioned by activin A-induced regulatory T cells exhibit enhanced tolerogenic properties and protect against experimental asthma.

BACKGROUND: Previously, we demonstrated that regulatory T (Treg) cells induced by the cytokine activin-A suppress TH2-mediated allergic responses and linked airway disease. Still, the effects of activin-A-induced regulatory T (Act-A-iTreg) cells on the regulation of dendritic cell (DC)-driven allergic inflammation remain elusive. OBJECTIVE: Here we investigated whether Act-A-iTreg cells can modulate DC responses and endow them with enhanced tolerogenic functions. METHODS: Using adoptive cell transfer studies in mouse models of allergic airway disease, we examined the effects of Act-A-iTreg cells on DC phenotype, maturation status, and TH2 cell priming potential. Genome-wide gene expression profiling characterized the transcriptional networks induced in tolerogenic DCs by Act-A-iTreg cells. The ability of DCs conditioned by Act-A-iTreg cells (Act-A-iTreg cell-modified DCs) to protect against experimental asthma, and the mechanisms involved were also explored. RESULTS: Act-A-iTreg cell-modified DCs exhibited a significantly impaired capacity to uptake allergen and stimulate naive and TH2 effector responses on allergen stimulation in vivo accompanied by markedly attenuated inflammatory cytokine release in response to LPS. Gene-profiling studies revealed that Act-A-iTreg cells dampened crucial TH2-skewing transcriptional networks in DCs. Administration of Act-A-iTreg cell-modified DCs ameliorated cardinal asthma manifestations in preventive and therapeutic protocols through generation of strongly suppressive forkhead box P3+ Treg cells. Finally, programed death protein 1/programmed death ligand 1 signaling pathways were essential in potentiating the generation of DCs with tolerogenic properties by Act-A-iTreg cells. CONCLUSION: Our studies reveal that Act-A-iTreg cells instruct the generation of a highly effective immunoregulatory circuit encompassing tolerogenic DCs and forkhead box P3+ Treg cells that could be targeted for the design of novel immunotherapies for allergic disorders.

Mechanism of chimeric vaccine stimulation of indoleamine 2,3-dioxygenase biosynthesis in human dendritic cells is independent of TGF-ß signaling.

Cholera toxin B subunit fusion to autoantigens such as proinsulin (CTB-INS) down regulate dendritic cell (DC) activation and stimulate synthesis of DC immunosuppressive cytokines. Recent studies of CTB-INS induction of immune tolerance in human DCs indicate that increased biosynthesis of indoleamine 2,3-dioxygenase (IDO1) may play an important role in CTB-INS vaccine suppression of DC activation. Studies in murine models suggest a role for transforming growth factor beta (TGF-ß) in the stimulation of IDO1 biosynthesis, for the induction of tolerance in DCs. Here, we investigated the contribution of TGF-ß superfamily proteins to CTB-INS induction of IDO1 biosynthesis in human monocyte-derived DCs (moDCs). We show that CTB-INS upregulates the level of TGF-ß1, activin-A and the TGF-ß activator, integrin αvß8 in human DCs. However, inhibition of endogenous TGF-ß, activin-A or addition of biologically active TGF-ß1, and activin-A, did not inhibit or stimulate IDO1 biosynthesis in human DCs treated with CTB-INS. While inhibition with the kinase inhibitor, RepSox, blocked SMAD2/3 phosphorylation and diminished IDO1 biosynthesis in a concentration dependent manner. Specific blocking of the TGF-ß type 1 kinase receptor with SB-431542 did not arrest IDO1 biosynthesis, suggesting the involvement of a different kinase pathway other than TGF-ß type 1 receptor kinase in CTB-INS induction of IDO1 in human moDCs. Together, our experimental findings identify additional immunoregulatory proteins induced by the CTB-INS fusion protein, suggesting CTB-INS may utilize multiple mechanisms in the induction of tolerance in human moDCs.

Cardiokines as Modulators of Stress-Induced Cardiac Disorders.

Almost 30 years ago, the protein, atrial natriuretic peptide, was identified as a heart-secreted hormone that provides a peripheral signal from the myocardium that communicates to the rest of the organism to modify blood pressure and volume under conditions of heart failure. Since then, additional peripheral factors secreted by the heart, termed cardiokines, have been identified and shown to coordinate this interorgan cross talk. In addition to this interorgan communication, cardiokines also act in an autocrine/paracrine manner to play a role in intercellular communication within the myocardium. This review focuses on the roles of newly emerging cardiokines that are mainly increased in stress-induced cardiac diseases. The potential of these cardiokines as clinical biomarkers for diagnosis and prognosis of cardiac disorders is also discussed.

BAFF and APRIL from Activin A-Treated Dendritic Cells Upregulate the Antitumor Efficacy of Dendritic Cells In Vivo.

The members of the TGFß superfamily play a key role in regulating developmental and homeostasis programs by controlling differentiation, proliferation, polarization, and survival of different cell types. Although the role of TGFß1 in inflammation and immunity is well evident, the contribution of other TGFß family cytokines in the modulation of the antitumor immune response remains less documented. Here we show that activin A triggers SMAD2 and ERK1/2 pathways in dendritic cells (DC) expressing type I and II activin receptors, and upregulates production of the TNFα family cytokines BAFF (TALL-1, TNFSF13B) and APRIL (TALL-2, TNFSF13A), which is blocked by SMAD2 and ERK1/2 inhibitors, respectively. BAFF and APRIL derived from activin A-treated DCs upregulate proliferation and survival of T cells expressing the corresponding receptors, BAFF-R and TACI. In vivo, activin A-stimulated DCs demonstrate a significantly increased ability to induce tumor-specific CTLs and inhibit the growth of melanoma and lung carcinoma, which relies on DC-derived BAFF and APRIL, as knockdown of the BAFF and APRIL gene expression in activin A-treated DCs blocks augmentation of their antitumor potential. Although systemic administration of activin A, BAFF, or APRIL for the therapeutic purposes is not likely due to the pluripotent effects on malignant and nonmalignant cells, our data open a novel opportunity for improving the efficacy of DC vaccines. In fact, a significant augmentation of the antitumor activity of DC pretreated with activin A and the proven role of DC-derived BAFF and APRIL in the induction of antitumor immunity in vivo support this direction. Cancer Res; 76(17); 4959-69. ©2016 AACR.

Atypical Activin A and IL-10 Production Impairs Human CD16+ Monocyte Differentiation into Anti-Inflammatory Macrophages.

Human CD14(++)CD16(-) and CD14(+/lo)CD16(+) monocyte subsets comprise 85 and 15% of blood monocytes, respectively, and are thought to represent distinct stages in the monocyte differentiation pathway. However, the differentiation fates of both monocyte subsets along the macrophage (Mϕ) lineage have not yet been elucidated. We have now evaluated the potential of CD14(++) CD16(-) and CD16(+) monocytes to differentiate and to be primed toward pro- or anti-inflammatory Mϕs upon culture with GM-CSF or M-CSF, respectively (subsequently referred to as GM14, M14, GM16, or M16). Whereas GM16 and GM14 were phenotypic and functionally analogous, M16 displayed a more proinflammatory profile than did M14. Transcriptomic analyses evidenced that genes associated with M-CSF-driven Mϕ differentiation (including FOLR2, IL10, IGF1, and SERPINB2) are underrepresented in M16 with respect to M14. The preferential proinflammatory skewing of M16 relative to M14 was found to be mediated by the secretion of activin A and the low levels of IL-10 produced by M16. In fact, activin A receptor blockade during the M-CSF-driven differentiation of CD16(+) monocytes, or addition of IL-10-containing M14-conditioned medium, significantly enhanced their expression of anti-inflammatory-associated molecules while impairing their acquisition of proinflammatory-related markers. Thus, we propose that M-CSF drives CD14(++)CD16- monocyte differentiation into bona fide anti-inflammatory Mϕs in a self-autonomous manner, whereas M-CSF-treated CD16(+) monocytes generate Mϕs with a skewed proinflammatory profile by virtue of their high activin A expression unless additional anti-inflammatory stimuli such as IL-10 are provided.

Possible involvement of inflammatory/reparative processes in the development of uterine fibroids.

Uterine leiomyomas are benign tumors in the smooth muscle layer of the uterus. The most common histological type is the "usual leiomyoma", characterized by overexpression of ECM proteins, whereas the "cellular type" has higher cellular content. Our objective is to investigate the involvement of inflammatory and reparative processes in leiomyoma pathobiology. Using a morphological approach, we investigate the presence of inflammatory cells. Next, we determine the localization of the ECM, the presence/absence of fibrotic cells via α-sma and desmin and the immunohistochemical profile of the mesenchymal cells with respect to CD34. Finally, we explore the effect of inflammatory mediators (TNF-α, IL-1ß, IL-6, IL-15, GM-CSF and IFN-γ) on pro-fibrotic factor activin A mRNA expression in vitro. Higher numbers of macrophages were found inside and close to leiomyomas as compared to the more distant myometrium. Cellular leiomyomas showed more macrophages and mast cells than the "usual type". Inside the fibroid tissue, we found cells positive for α-sma, but negative for desmin and a large amount of collagen surrounding the nodule, suggestive of myofibroblasts producing ECM. In the myometrium and leiomyomas of the "usual type", we identified numerous CD34+ fibroblasts, which are known to give rise to myofibroblasts upon loss of CD34 expression. In leiomyomas of the "cellular type", stromal fibroblasts were CD34-negative. Finally, we found that TNF-α increased activin A mRNA in myometrial and leiomyoma cells. In conclusion, this study demonstrates the presence of inflammatory cells in uterine leiomyomas, which may contribute to excessive ECM production, tissue remodeling and leiomyoma growth.

The TGF-ß superfamily in dendritic cell biology.

The TGF-ß superfamily consists of a large group of pleiotropic cytokines that are involved in the regulation of many developmental, physiological and pathological processes. Dendritic cells are antigen-presenting cells that play a key role in innate and adaptive immune responses. Dendritic cells have a complex relationship with the TGF-ß cytokine superfamily being both source and targets for many of these cytokines. Some TGF-ß family members are expressed by dendritic cells and modulate immune responses, for instance through the induction of T cell polarization. Others play a crucial role in the development and function of the different dendritic cell subsets. This review summarizes the current knowledge on the role of TGF-ß family cytokines in dendritic cell biology, focusing on TGF-ß as well as on other, less characterized, members of these important immune mediators.

The immunoregulatory and fibrotic roles of activin A in allergic asthma.

Activin A, a member of the TGF-ß superfamily of cytokines, was originally identified as an inducer of follicle stimulating hormone release, but has since been ascribed roles in normal physiological processes, as an immunoregulatory cytokine and as a driver of fibrosis. In the last 10-15 years, it has also become abundantly clear that activin A plays an important role in the regulation of asthmatic inflammation and airway remodelling. This review provides a brief introduction to the activin A/TGF-ß superfamily, focussing on the regulation of receptors and signalling pathways. We examine the contradictory evidence for generalized pro- vs. anti-inflammatory effects of activin A in inflammation, before appraising its role in asthmatic inflammation and airway remodelling specifically by evaluating data from both murine models and clinical studies. We identify key issues to be addressed, paving the way for safe exploitation of modulation of activin A function for treatment of allergic asthma and other inflammatory lung diseases.

Cyclic stretch augments production of neutrophil chemokines, matrix metalloproteinases, and activin a in human endometrial stromal cells.

PROBLEM: The aim of this study was to test our hypothesis: Contractile activity that occurs in the uterus during menstruation induces biochemical factors that enhance remodeling of the endometrium. METHOD OF STUDY: Cyclic stretch, mimicking contractile activity during menstruation, was applied to human endometrial stromal cells (ESC) using the Flexercell Tension system. The concentration and activity of CXCL8, CXCL1, MMPs, and activin A were measured using ELISAs and specific assays. Neutrophil chemotactic activity was evaluated using migration assays. RESULTS: Cyclic stretch significantly induced ESC secretion of CXCL8 and CXCL1 and neutrophil chemotaxis. Stretch also increased MMP-1, MMP-2, and MMP-3 activity, activin A secretion, and activity in ESC. CONCLUSION: These results indicate that the contractile activities of the uterus during menstruation contribute to the remodeling of the endometrium, by inducing chemokine secretion, MMP expression, activity, and neutrophil chemotaxis.