Activin A is a critical component of the inflammatory response, and its binding protein, follistatin, reduces mortality in endotoxemia

Activin A impairs ActRIIA+ neutrophil recruitment into infected skin of mice

Activin A levels are elevated during multiple severe infections and associated with an increased risk of death. However, the role of activin A in bacterial infection is still unclear. Here, we found that activin A levels were increased during S. aureus skin infection in mice. Administration of activin A increased the bacterial burden and promoted the spread of bacteria in vivo. Moreover, activin A inhibited neutrophil chemotaxis to N-formylmethionine-leucyl-phenylalanine via the type IIA activin receptor (ActRIIA) in vitro and impaired ActRIIA⁺ neutrophil recruitment to infection foci in vivo. Additionally, we identified a novel subpopulation of neutrophils, ActRIIA⁺ neutrophils, which exhibit superior phagocytic capacity compared to ActRIIA⁻ neutrophils and possess an N2-like immunoregulatory activity via secreting IL-10 and TGF-β. Taken together, these findings indicate that activin A inhibits the recruitment of ActRIIA⁺ neutrophils to infected foci, leading to the impairment of bacterial clearance, and thus may hamper early infection control.

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A novel activin A-responsitive subpopulation of neutrophils (ActRIIA⁺) was identified

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ActRIIA⁺ neutrophils exhibit N2-like immunoregulatory properties

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Activin A inhibits ActRIIA⁺ neutrophil recruitment to infected skin

NRF2 -617 C/A Polymorphism Impacts Proinflammatory Cytokine Levels, Survival, and Transplant-Related Mortality After Hematopoietic Stem Cell Transplantation in Adult Patients Receiving Busulfan-Based Conditioning Regimens

Busulfan (BU) is widely used in conditioning regimens prior to hematopoietic stem cell transplantation (HSCT). The exposure-escalated BU directed by therapeutic drug monitoring (TDM) is extremely necessary for the patients with high-risk hematologic malignancies in order to diminish relapse, but it increases the risk of drug-induced toxicity. BU exposure, involved in the glutathione- (GSH-) glutathione S-transferases (GSTs) pathway and proinflammatory response, is associated with clinical outcomes after HSCT. However, the expression of genes in the GSH-GSTs pathway is regulated by NF-E2-related factor 2 (Nrf2) that can also alleviate inflammation. In this study, we evaluated the influence of NRF2 polymorphisms on BU exposure, proinflammatory cytokine levels, and clinical outcomes in HSCT patients. A total of 87 Chinese adult patients receiving twice-daily intravenous BU were enrolled. Compared with the patients carrying wild genotypes, those with NRF2 -617 CA/AA genotypes showed higher plasma interleukin (IL)-6, IL-8 and tumor necrosis factor (TNF)-α levels, poorer overall survival (OS; RR = 3.91), and increased transplant-related mortality (TRM; HR = 4.17). High BU exposure [area under the concentration-time curve (AUC) > 9.27 mg/L × h)] was related to BU toxicities. Furthermore, NRF2 -617 CA/AA genotypes could significantly impact TRM (HR = 4.04; p = 0.0142) and OS (HR = 3.69; p = 0.0272) in the patients with high BU AUC. In vitro, we found that high exposure of endothelial cell (EC) to BU, in the absence of Nrf2, elicited the hyperstimulation of NF-κB-p65, accompanied with the elevated secretion of proinflammatory cytokines, and led to EC death. These results showed that NRF2 -617 CA/AA genotypes, correlated with high proinflammatory cytokine levels, could predict inferior outcomes in HSCT patients with high BU AUC. Thus, NRF2 -617 CA/AA genotyping combined with TDM would further optimize personalized BU dosing for sufficient efficacy and safety endpoint.

Possible Role of Activin in the Adiponectin Paradox-Induced Progress of Alzheimer's Disease

Accumulating evidence suggests that the adiponectin (APN) paradox might be involved in promoting aging-associated chronic diseases such as Alzheimer's disease (AD). In human brain, APN regulation of the evolvability of amyloidogenic proteins (APs), including amyloid-β (Aβ) and tau, in developmental/reproductive stages, might be paradoxically manifest as APN stimulation of AD through antagonistic pleiotropy in aging. The unique mechanisms underlying APN activity remain unclear, a better understanding of which might provide clues for AD therapy. In this paper, we discuss the possible relevance of activin, a member of transforming growth factor β (TGFβ) superfamily of peptides, to antagonistic pleiotropy effects of APN. Notably, activin, a multiple regulator of cell proliferation and differentiation, as well as an endocrine modulator in reproduction and an organizer in early development, might promote aging-associated disorders, such as inflammation and cancer. Indeed, serum activin, but not serum TGFβ increases during aging. Also, activin/TGFβ signal through type II and type I receptors, both of which are transmembrane serine/threonine kinases, and the serine/threonine phosphorylation of APs, including Aβ42 serine 8 and αS serine 129, may confer pathological significance in neurodegenerative diseases. Moreover, activin expression is induced by APN in monocytes and hepatocytes, suggesting that activin might be situated downstream of the APN paradox. Finally, a meta-analysis of genome-wide association studies demonstrated that two SNPs relevant to the activin/TGFβ receptor signaling pathways conferred risk for major aging-associated disease. Collectively, activin might be involved in the APN paradox of AD and could be a significant therapeutic target.

Cytokine activin C ameliorates chronic neuropathic pain in peripheral nerve injury rodents by modulating the TRPV1 channel

BACKGROUND AND PURPOSE

The cytokine activin C is mainly expressed in small-diameter dorsal root ganglion (DRG) neurons and suppresses inflammatory pain. However, the effects of activin C in neuropathic pain remain elusive.

EXPERIMENTAL APPROACH

Male rats and wild-type and TRPV1 knockout mice with peripheral nerve injury - sciatic nerve axotomy and spinal nerve ligation in rats; chronic constriction injury (CCI) in mice - provided models of chronic neuropathic pain. Ipsilateral lumbar (L)4-5 DRGs were assayed for activin C expression. Chronic neuropathic pain animals were treated with intrathecal or locally pre-administered activin C or the vehicle. Nociceptive behaviours and pain-related markers in L4-5 DRGs and spinal cord were evaluated. TRPV1 channel modulation by activin C was measured.

KEY RESULTS

Following peripheral nerve injury, expression of activin βC subunit mRNA and activin C protein was markedly up-regulated in L4-5 DRGs of animals with axotomy, SNL or CCI. [Correction added on 26 November 2020, after first online publication: The preceding sentence has been corrected in this current version.] Intrathecal activin C dose-dependently inhibited neuropathic pain in spinal nerve ligated rats. Local pre-administration of activin C decreased neuropathic pain, macrophage infiltration into ipsilateral L4-5 DRGs and microglial reaction in L4-5 spinal cords of mice with CCI. In rat DRG neurons, activin C enhanced capsaicin-induced TRPV1 currents. Pre-treatment with activin C reduced capsaicin-evoked acute hyperalgesia and normalized capsaicin-evoked persistent hypothermia in mice. Finally, the analgesic effect of activin C was abolished in TRPV1 knockout mice with CCI.

CONCLUSION AND IMPLICATIONS

Activin C inhibits neuropathic pain by modulating TRPV1 channels, revealing potential analgesic applications in chronic neuropathic pain therapy.

Antagonistic effects of activin A and TNF-α on the activation of L929 fibroblast cells via Smad3-independent signaling

Fibroblasts play an important role in inflammation and tissue fibrosis. Both activin A and TNF-α can activate immune cells, however, the roles and relationship of them in activating fibroblasts in inflammation remain unclear. Here, this study revealed that TNF-α promoted the release of NO and IL-6 by L929 fibroblast cells, but co-treatment with activin A attenuated these effects. In contrast, activin A induced cell migration and increased the production of tissue fibrosis-related TGF-β1 and fibronectin, while TNF-α inhibited these function changes of L929 cells induced by activin A. Moreover, this study revealed that activin A and TNF-α regulated the activities of L929 cells via ERK1/2/MAPK pathway, rather than Smad3-dependent signaling pathway. Taken together, these data indicate that activin A and TNF-α exert mutually antagonistic effects on regulating fibroblasts activities, and the balance between their action may determine the process and outcome of fibroblasts-mediated inflammation.

Dynamics of Transforming Growth Factor (TGF)-β Superfamily Cytokine Induction During HIV-1 Infection Are Distinct From Other Innate Cytokines

Human immunodeficiency virus type 1 (HIV-1) infection triggers rapid induction of multiple innate cytokines including type I interferons, which play important roles in viral control and disease pathogenesis. The transforming growth factor (TGF)-β superfamily is a pleiotropic innate cytokine family, some members of which (activins and bone morphogenetic proteins (BMPs)) were recently demonstrated to exert antiviral activity against Zika and hepatitis B and C viruses but are poorly studied in HIV-1 infection. Here, we show that TGF-β₁ is systemically induced with very rapid kinetics (as early as 1-4 days after viremic spread begins) in acute HIV-1 infection, likely due to release from platelets, and remains upregulated throughout infection. Contrastingly, no substantial systemic upregulation of activins A and B or BMP-2 was observed during acute infection, although plasma activin levels trended to be elevated during chronic infection. HIV-1 triggered production of type I interferons but not TGF-β superfamily cytokines from plasmacytoid dendritic cells (DCs) in vitro, putatively explaining their differing in vivo induction; whilst lipopolysaccharide (but not HIV-1) elicited activin A production from myeloid DCs. These findings underscore the need for better definition of the protective and pathogenic capacity of TGF-β superfamily cytokines, to enable appropriate modulation for therapeutic purposes.

Metabolic regulation of activins in healthy individuals and in obese patients undergoing bariatric surgery

OBJECTIVE

Follistatin binds and inactivates activins, which are potent inhibitors of muscle growth and metabolism and are currently being developed for the treatment of obesity and type 2 diabetes (T2D). We have recently reported that follistatin is regulated by glucose (and not lipids) and can prospectively predict the metabolic improvements observed after bariatric surgery. We utilized novel assays herein to investigate whether activins are regulated by glucose or lipids, whether their circulating levels change after bariatric surgery and whether these changes are predictors of metabolic outcomes up to 12 months later.

DESIGN AND METHODS

Activin A, B, AB and their ratios to follistatin were measured in (a) healthy humans (n = 32) undergoing oral or intravenous lipid or glucose intake over 6 h, (b) morbidly obese individuals with or without type 2 diabetes undergoing three different types of bariatric surgery (gastric banding, Roux-en-Y bypass or sleeve gastrectomy) in two clinical studies (n = 14 for the first and n = 27 for the second study).

RESULTS

Glucose intake downregulates circulating activin A, B and AB, indicating the presence of a feedback loop. Activin A decreases (~30%), activin AB increases (~25%) and activin B does not change after bariatric surgery. The changes in activin AB and its ratio to follistatin 3 months after bariatric surgery can predict the BMI reduction and the improvement in insulin and HOMA-IR observed 6 months postoperatively.

CONCLUSION

Activins are implicated in glucose regulation in humans as part of a feedback loop with glucose or insulin and predict metabolic outcomes prospectively after bariatric surgery.

Growth Hormone Reprograms Macrophages toward an Anti-Inflammatory and Reparative Profile in an MAFB-Dependent Manner

Growth hormone (GH), a pleiotropic hormone secreted by the pituitary gland, regulates immune and inflammatory responses. In this study, we show that GH regulates the phenotypic and functional plasticity of macrophages both in vitro and in vivo. Specifically, GH treatment of GM-CSF-primed monocyte-derived macrophages promotes a significant enrichment of anti-inflammatory genes and dampens the proinflammatory cytokine profile through PI3K-mediated downregulation of activin A and upregulation of MAFB, a critical transcription factor for anti-inflammatory polarization of human macrophages. These in vitro data correlate with improved remission of inflammation and mucosal repair during recovery in the acute dextran sodium sulfate-induced colitis model in GH-overexpressing mice. In this model, in addition to the GH-mediated effects on other immune cells, we observed that macrophages from inflamed gut acquire an anti-inflammatory/reparative profile. Overall, these data indicate that GH reprograms inflammatory macrophages to an anti-inflammatory phenotype and improves resolution during pathologic inflammatory responses.

Sustained exposure to systemic endotoxin triggers chemokine induction in the brain followed by a rapid influx of leukocytes

Background

Recent years have seen an explosion of research pertaining to biological psychiatry, yet despite subsequent advances in our understanding of neuroimmune communication pathways, how the brain senses and responds to peripheral inflammation remains poorly understood. A better understanding of these pathways may be important for generating novel therapeutics to treat many patients with chronic inflammatory diseases who also suffer from neuropsychiatric comorbidities. Here we have systematically assessed the leukocyte infiltrate to the brain following systemic endotoxin exposure to better understand this novel route of neuroimmune communication.

Methods

Mice were injected intraperitoneally with LPS daily for 2, 5 or 7 consecutive days. We systematically interrogated the subsequent induction of chemokine transcription in the brain using TaqMan low-density arrays. A combination of flow cytometry and immunohistochemistry was then used to characterise the accompanying leukocyte infiltrate.

Results

Repeated LPS challenges resulted in prolonged activation of brain-resident microglia, coupled with an increased local transcription of numerous chemokines. After 2 days of administering LPS, there was a marked increase in the expression of the neutrophil chemoattractants CXCL1 and CXCL2; the monocyte chemoattractants CCL2, CCL5, CCL7 and CCL8; and the lymphocyte chemoattractants CXCL9, CXCL10 and CXCL16. In a number of cases, this response was sustained for several days. Chemokine induction was associated with a transient recruitment of neutrophils and monocytes to the brain, coupled with a sustained accumulation of macrophages, CD8+ T cells, NK cells and NKT cells. Strikingly, neutrophils, monocytes and T cells appeared to extravasate from the vasculature and/or CSF to infiltrate the brain parenchyma.

Conclusions

Prolonged exposure to a peripheral inflammatory stimulus triggers the recruitment of myeloid cells and lymphocytes to the brain. By altering the inflammatory or metabolic milieu of the brain, this novel method of immune-to-brain communication may have profound implications for patients with chronic inflammatory diseases, potentially leading to neuropsychiatric comorbidities.

Intravascular Follistatin gene delivery improves glycemic control in a mouse model of type 2 diabetes

Type 2 diabetes (T2D) manifests from inadequate glucose control due to insulin resistance, hypoinsulinemia, and deteriorating pancreatic β-cell function. The pro-inflammatory factor Activin has been implicated as a positive correlate of severity in T2D patients, and as a negative regulator of glucose uptake by skeletal muscle, and of pancreatic β-cell phenotype in mice. Accordingly, we sought to determine whether intervention with the Activin antagonist Follistatin can ameliorate the diabetic pathology. Here, we report that an intravenous Follistatin gene delivery intervention with tropism for striated muscle reduced the serum concentrations of Activin B and improved glycemic control in the db/db mouse model of T2D. Treatment reversed the hyperglycemic progression with a corresponding reduction in the percentage of glycated-hemoglobin to levels similar to lean, healthy mice. Follistatin gene delivery promoted insulinemia and abundance of insulin-positive pancreatic β-cells, even when treatment was administered to mice with advanced diabetes, supporting a mechanism for improved glycemic control associated with maintenance of functional β-cells. Our data demonstrate that single-dose intravascular Follistatin gene delivery can ameliorate the diabetic progression and improve prognostic markers of disease. These findings are consistent with other observations of Activin-mediated mechanisms exerting deleterious effects in models of obesity and diabetes, and suggest that interventions that attenuate Activin signaling could help further understanding of T2D and the development of novel T2D therapeutics.

Activin A Expressed in Rheumatoid Synovial Cells Downregulates TNFα-Induced CXCL10 Expression and Osteoclastogenesis

OBJECTIVE

Activin A is known to be highly expressed in rheumatoid synovium. In the present study, we investigated the effect of inflammatory cytokines on activin A production and its role in rheumatoid inflammation using freshly prepared rheumatoid synovial cells (fresh-RSC).

METHODS

Fresh-RSC from patients with rheumatoid arthritis were obtained and stimulated with multiple cytokines for activin A production. Gene expression levels of activin A and inflammatory cytokines were determined by quantitative PCR (qPCR) analysis. An enzyme-linked immunosorbent assay (ELISA) was used to measure activin A and CXCL10 in culture supernatants. The osteoclasts generated from human peripheral monocytes by RANKL stimulation were identified by tartrate-resistant acid phosphatase staining and bone resorption assay using Osteo plate. The expression levels of NFATc1 and cathepsin K, critical intracellular proteins for osteoclastogenesis, were determined by Western blotting.

RESULTS

Activin A production in fresh-RSC was markedly enhanced by the synergistic effect of TGF-β1 with inflammatory cytokines, including TNFα, IL-1β, and IL-6. Activin A inhibited TNFα-induced CXCL10, an important chemoattractant for pathogen-activated T cells and monocytes of osteoclast precursors, but it did not affect the expression of inflammatory cytokines and chemokines. In addition, activin A directly inhibited the expression of NFATc1 and cathepsin K, as well as osteoclast formation in human samples.

CONCLUSION

Our data indicated that TGF-β1 is involved in the expression of activin A at inflamed joints. Activin A mainly exerts an anti-inflammatory action, which prevents joint damage via the regulation of CXCL10 and osteoclastogenesis.

Intraperitoneal administration of activin A promotes development of endometriotic lesions in a mouse model of endometriosis

PURPOSE

This study aimed to investigate the effect of intraperitoneal administration of activin on the occurrence of endometriosis using a mouse model of endometriosis.

METHODS

A mouse model of endometriosis was prepared by intraperitoneally administering endometrial tissue and blood collected from donor mice to C57BL/6J 7-8- week-old recipient mice. A total of 400 μg of activin A was intraperitoneally administered to model mice in the activin group for 5 days. Intraperitoneal endometriotic lesions were confirmed macroscopically and IL-6 and TNF-α levels in washed ascites were measured by ELISA.

RESULTS

Endometriotic lesions were observed in all mice. In the activin group, the maximum diameter of endometriotic lesions was significantly larger than that in control group (4.7?1.3 vs 2.9?0.9 mm, p?0.01). The total area of the lesion was also significantly higher in the activin group than in the control group (21.1?9.9 vs 8.8?5.4 mm²,p?0.01). Furthermore, IL-6 and TNF-α levels in ascites were significantly higher in the activin group than in the control group (IL-6 : 85.8?15.3 vs 75.1?19.3 pg/ml, p?0.05 ; TNF-α : 629.8?15.4 vs 605.9?11.4 pg/ml, p?0.05).

CONCLUSION

Activin promotes occurrence of endometriosis. Inflammatory cytokines are also elevated by activin administration,suggesting that they may contribute to progression of endometriosis J. Med. Invest. 66 : 123-127, February, 2019.

Acute heat-treatment disrupts inhibin-related protein production and gene expression in the adult rat testis

Heat reversibly disrupts spermatogenesis, but the effects on Sertoli cell (SC) function and inhibin/activin-related proteins are less well-defined. Adult rat testis weights decreased by 40% within 2 weeks after heat-treatment (43 °C, 15 min), due to loss of pachytene spermatocytes and round spermatids. Coincident effects were reduced SC nuclear volume at one week and >50% reduction in expression of several critical SC genes (Inha, Cld11, Gja1, Tjp1, Cldn3) by 2 weeks. Leydig cell steroidogenic enzymes, Cyp11a1, Hsd3b1, were also reduced. Activin gene expression was unaffected at this time, but expression of the activin-binding protein, follistatin (Fst), increased >2-fold. At 4-8 weeks, coincident with the recovery of spermatocytes and early spermatids, but progressive loss of elongated spermatids, most SC genes had recovered; however, testicular activin A was reduced and activin B increased. At 8 weeks, serum inhibin was decreased and, consequently, serum FSH increased. Crucially, germ cell damage was not associated with a significant inflammatory response. At 14 weeks, most testicular parameters had returned to normal, but testis weights remained slightly reduced. These data indicate that, following acute heat-treatment, expression of several key Sertoli and Leydig cell genes declined in parallel with the initial loss of meiotic germ cells, whereas activins were responsive to the subsequent loss of mature spermatids, leading to an increase in testicular activin B production relative to activin A.

Neutrophil activation in septic acute kidney injury: A post hoc analysis of the FINNAKI study

BACKGROUND

Inflammation, reflected by high plasma interleukin-6 concentration, is associated with acute kidney injury (AKI) in septic patients. Neutrophil activation has pathophysiological significance in experimental septic AKI. We hypothesized that neutrophil activation is associated with AKI in critically ill sepsis patients.

METHODS

We measured plasma (n = 182) and urine (n = 118) activin A (a rapidly released cytosolic neutrophil protein), interleukin-8 (a chemotactic factor for neutrophils), myeloperoxidase (a neutrophil biomarker released in tissues), and interleukin-6 on intensive care unit admission (plasma and urine) and 24 hours later (plasma) in sepsis patients manifesting their first organ dysfunction between 24 hours preceding admission and the second calendar day in intensive care unit. AKI was defined by the Kidney Disease: Improving Global Outcomes criteria.

RESULTS

Plasma admission interleukin-8 (240 [60-971] vs 50 [19-164] pg/mL, P < .001) and activin A (845 [554-1895] vs 469 [285-862] pg/mL, P < .001) were but myeloperoxidase (169 [111-300] vs 144 [88-215] ng/mL, P = .059) was not higher among patients with AKI compared with those without. Urine admission interleukin-8 (50.4 [19.8-145.3] vs 9.5 [2.7-28.7] ng/mL, P < .001) and myeloperoxidase (7.7 [1.5-12.6] vs 1.9 [0.4-6.9] ng/mL, P < .001) were but activin A (9.7 [1.4-42.6] vs 4.0 [0.0-33.0] ng/mL, P = .064) was not higher in AKI than non-AKI patients. Urine myeloperoxidase correlated with urine interleukin-8 (R = .627, P < .001) but not with plasma myeloperoxidase (R = .131, P = .158).

CONCLUSION

Interleukin-8 in plasma and urine was associated with septic AKI. Elevated plasma activin A indicates intravascular neutrophil activation in septic AKI. Concomitant plasma and urine myeloperoxidase measurements suggest neutrophil accumulation into injured kidneys.

Elevated Circulating Activin A Levels in Patients With Malignant Pleural Mesothelioma Are Related to Cancer Cachexia and Reduced Response to Platinum-based Chemotherapy

BACKGROUND

Previous preclinical studies have shown that activin A is overexpressed in malignant pleural mesothelioma (MPM), associates with cancer cachexia, and is observed in in vitro resistance to platinum-based chemotherapy. We evaluated circulating activin levels and their endogenous antagonists' follistatin/follistatin-like 3 in intrathoracic tumors.

MATERIALS AND METHODS

Patients suspected of thoracic malignancy were recruited prior to surgery. Serum samples were collected from 21 patients with MPM, 59 patients with non-small-cell lung cancer (NSCLC), and 22 patients with benign lung lesions. Circulating activin/follistatin levels were measured using enzyme-linked immunosorbent assay and compared with clinicopathologic parameters.

RESULTS

Circulating activin A levels were elevated in patients with MPM when compared with patients with NSCLC or benign lung lesion samples (P < .0001). Also, follistatin and follistatin-like 3 levels were the highest in MPM, although with less difference compared with activin A. Receiver operating characteristic analysis for activin A for separating NSCLC from benign lung lesion showed an area under the curve of 0.856 (95% confidence interval, 0.77-0.94). Activin A levels were higher in patients with cachexia (P < .001). In patients with MPM, activin A levels correlated positively with computed tomography-based baseline tumor size (R = 0.549; P = .010) and the change in tumor size after chemotherapy (R = 0.743; P = .0006). Patients with partial response or stable disease had lower circulating activin A levels than the ones with progressive disease (P = .028).

CONCLUSION

Activin A serum level could be used as a biomarker in differentiating malignant and benign lung tumors. Circulating activin A levels were elevated in MPM and associates with cancer cachexia and reduced chemotherapy response.

Allergen-induced asthma, chronic rhinosinusitis and transforming growth factor-β superfamily signaling: mechanisms and functional consequences

Introduction: Often co-associated, asthma and chronic rhinosinusitis (CRS) are complex heterogeneous disease syndromes. Severity in both is related to tissue inflammation and abnormal repair (termed remodeling). Understanding signaling factors that can modulate, integrate the activation, and regulation of such key processes together is increasingly important. The transforming growth factor (TGF)-β superfamily of ligands comprise a versatile system of immunomodulatory molecules that are gaining recognition as having an essential function in the immunopathogenesis of asthma. Early data suggest an important role in CRS as well. Abnormal or dysregulated signaling may contribute to disease pathogenesis and severity.Areas covered: The essential biology of this complex family of growth factors in relation to the excess inflammation and remodeling that occurs in allergic asthma and CRS is reviewed. The need to understand the integration of signaling pathways together is highlighted. Studies in human airway tissue are evaluated and only selected key animal models relevant to human disease discussed given the highly context-dependent signaling and function of these ligands.Expert opinion: Abnormal or dysregulated TGF-β superfamily signaling may be central to the excess inflammation and tissue remodeling in asthma, and possibly CRS. Therefore, the TGF-β superfamily signaling pathways represent an emerging and attractive therapeutic target.

Urinary Activin A is a novel biomarker reflecting renal inflammation and tubular damage in ANCA-associated vasculitis

Activin A, a member of the transforming growth factor-beta superfamily, is a critical modulator of inflammation and plays a key role in controlling the cytokine cascade that drives the inflammatory response. However, the role of activin A in inflammatory kidney diseases remains unknown. To address this issue, we examined here whether activin A can be detected in the kidney and/or urine from patients with antineutrophil cytoplasmic antibody (ANCA) -associated vasculitis (AAV). Fifty-one patients who had been diagnosed with AAV and were treated in our department between November 2011 to March 2018 were included in this study. Forty-one patients had renal complications (renal AAV). Serum and urinary activin A levels were measured by enzyme-linked immunosorbent assay. Correlation of urinary activin A concentration with clinical parameters was analyzed. Urinary activin A was undetectable in healthy volunteers. In contrast, urinary activin A concentration was significantly increased in patients with renal AAV but not in those with non-renal AAV. Urinary activin A concentration decreased rapidly after immunosuppressive treatment. There was a significant correlation of urinary activin A level with urinary protein, L-FABP, and NAG. Histologic evaluation revealed that urinary activin A levels were significantly higher in patients with cellular crescentic glomeruli than in those lacking this damage. In situ hybridization demonstrated that the mRNA encoding the activin A βA subunit was undetectable in normal kidneys but accumulated in the proximal tubules and crescentic glomeruli of the kidneys of patients with renal AAV. Immunostaining showed that activin A protein also was present in the proximal tubules, crescentic glomeruli, and macrophages infiltrating into the interstitium in the kidneys of patients with renal AAV. These data suggested that urinary activin A concentration reflects renal inflammation and tubular damage in AAV and may be a useful biomarker for monitoring renal AAV.

TGFβ and activin A in the tumor microenvironment in colorectal cancer

Although overall survival in colorectal cancer (CRC) is increasing steadily due to progress in screening, therapeutic options and precise diagnostic tools remain scarce. As the understanding of CRC as a complex and multifactorial condition moves forward, the tumor microenvironment has come into focus as a source of diagnostic markers and potential therapeutic targets. The role of TGFβ in shifting the epithelial cancer compartment towards invasiveness and a pro-migratory phenotype via stromal signaling has been widely investigated. Accordingly, recent studies have proposed that CRC patients could be stratified into distinct subtypes and have identified one poor prognosis subset of CRC that is characterized by high stromal activity and elevated levels of TGFβ. The TGFβ superfamily member activin A is crucial for the pro-metastatic properties of the TGFβ pathway, yet it has been under-researched in CRC carcinogenesis. In this review, we will elucidate the signaling network and interdependency of both ligands in the context of the tumor microenvironment in CRC.

Cancer Takes a Toll on Skeletal Muscle by Releasing Heat Shock Proteins-An Emerging Mechanism of Cancer-Induced Cachexia

Cancer-associated cachexia (cancer cachexia) is a major contributor to the modality and mortality of a wide variety of solid tumors. It is estimated that cachexia inflicts approximately ~60% of all cancer patients and is the immediate cause of ~30% of all cancer-related death. However, there is no established treatment of this disorder due to the poor understanding of its underlying etiology. The key manifestations of cancer cachexia are systemic inflammation and progressive loss of skeletal muscle mass and function (muscle wasting). A number of inflammatory cytokines and members of the TGFβ superfamily that promote muscle protein degradation have been implicated as mediators of muscle wasting. However, clinical trials targeting some of the identified mediators have not yielded satisfactory results. Thus, the root cause of the muscle wasting associated with cancer cachexia remains to be identified. This review focuses on recent progress of laboratory studies in the understanding of the molecular mechanisms of cancer cachexia that centers on the role of systemic activation of Toll-like receptor 4 (TLR4) by cancer-released Hsp70 and Hsp90 in the development and progression of muscle wasting, and the downstream signaling pathways that activate muscle protein degradation through the ubiquitin-proteasome and the autophagy-lysosome pathways in response to TLR4 activation. Verification of these findings in humans could lead to etiology-based therapies of cancer cachexia by targeting multiple steps in this signaling cascade.

Common variable immunodeficiency-associated endotoxemia promotes early commitment to the T follicular lineage

BACKGROUND

Although chiefly a B-lymphocyte disorder, several research groups have identified common variable immunodeficiency (CVID) subjects with numeric and/or functional T_H cell alterations. The causes, interrelationships, and consequences of CVID-associated CD4⁺ T-cell derangements to hypogammaglobulinemia, autoantibody production, or both remain unclear.

OBJECTIVE

We sought to determine how circulating CD4⁺ T cells are altered in CVID subjects with autoimmune cytopenias (AICs; CVID+AIC) and the causes of these derangements.

METHODS

Using hypothesis-generating, high-dimensional single-cell analyses, we created comprehensive phenotypic maps of circulating CD4⁺ T cells. Differences between subject groups were confirmed in a large and genetically diverse cohort of CVID subjects (n = 69) by using flow cytometry, transcriptional profiling, multiplex cytokine/chemokine detection, and a suite of in vitro functional assays measuring naive T-cell differentiation, B-cell/T-cell cocultures, and regulatory T-cell suppression.

RESULTS

Although CD4⁺ T_H cell profiles from healthy donors and CVID subjects without AICs were virtually indistinguishable, T cells from CVID+AIC subjects exhibited follicular features as early as thymic egress. Follicular skewing correlated with IgA deficiency-associated endotoxemia and endotoxin-induced expression of activin A and inducible T-cell costimulator ligand. The resulting enlarged circulating follicular helper T-cell population from CVID+AIC subjects provided efficient help to receptive healthy donor B cells but not unresponsive CVID B cells. Despite this, circulating follicular helper T cells from CVID+AIC subjects exhibited aberrant transcriptional profiles and altered chemokine/cytokine receptor expression patterns that interfered with regulatory T-cell suppression assays and were associated with autoantibody production.

CONCLUSIONS

Endotoxemia is associated with early commitment to the follicular T-cell lineage in IgA-deficient CVID subjects, particularly those with AICs.

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

The TGF-β 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-β 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, T_FH 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.

Human organotypic lymphatic vessel model elucidates microenvironment-dependent signaling and barrier function

The lymphatic system is an active player in the pathogenesis of several human diseases, including lymphedema and cancer. Relevant models are needed to advance our understanding of lymphatic biology in disease progression to improve therapy and patient outcomes. Currently, there are few 3D in vitro lymphatic models that can recapitulate the physiological structure, function, and interactions of lymphatic vessels in normal and diseased microenvironments. Here, we developed a 3D microscale lymphatic vessel (μLYMPH) system for generating human lymphatic vessels with physiological tubular structure and function. Consistent with characteristics of lymphatic vessels in vivo, the endothelium of cultured vessels was leaky with an average permeability of 1.38 × 10^-5 ± 0.29 × 10^-5 cm/s as compared to 0.68 × 10^-5 ± 0.13 × 10^-5 cm/s for blood vessels. This leakiness also resulted in higher uptake of solute by the lymphatic vessels under interstitial flow, demonstrating recapitulation of their natural draining function. The vessels secreted appropriate growth factors and inflammatory mediators. Our system identified the follistatin/activin axis as a novel pathway in lymphatic vessel maintenance and inflammation. Moreover, the μLYMPH system provided a platform for examining crosstalk between lymphatic vessels and tumor microenvironmental components, such as breast cancer-associated fibroblasts (CAFs). In co-culture with CAFs, vessel barrier function was significantly impaired by CAF-secreted IL-6, a possible pro-metastatic mechanism of lymphatic metastasis. Targeted blocking of the IL-6/IL-6R signaling pathway with an IL-6 neutralizing antibody fully rescued the vessels, demonstrating the potential of our system for screening therapeutic targets. These results collectively demonstrate the μLYMPH system as a powerful model for advancing lymphatic biology in health and disease.

Therapeutic advances for blocking heterotopic ossification in fibrodysplasia ossificans progressiva

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disease in which heterotopic bone forms in muscle and soft tissue, leading to joint dysfunction and significant disability. FOP is progressive and many patients are wheelchair-bound by the 3rd decade of life. FOP is caused by an activating mutation in the ACVR1 gene, which encodes the activin A Type 1 receptor. Aberrant signalling through this receptor leads to abnormal activation of the pSMAD 1/5/8 pathway and triggers the formation of bone outside of the skeleton. There is no curative therapy for FOP; however, exciting advances in novel therapies have developed recently. Here, we review the clinical and translational pharmacology of three drugs that are currently in clinical trials (palovarotene, REGN 2477 and rapamycin) as well as other emerging treatment strategies for FOP.

Activin A in Mammalian Physiology

Activins are dimeric glycoproteins belonging to the transforming growth factor beta superfamily and resulting from the assembly of two beta subunits, which may also be combined with alpha subunits to form inhibins. Activins were discovered in 1986 following the isolation of inhibins from porcine follicular fluid, and were characterized as ovarian hormones that stimulate follicle stimulating hormone (FSH) release by the pituitary gland. In particular, activin A was shown to be the isoform of greater physiological importance in humans. The current understanding of activin A surpasses the reproductive system and allows its classification as a hormone, a growth factor, and a cytokine. In more than 30 yr of intense research, activin A was localized in female and male reproductive organs but also in other organs and systems as diverse as the brain, liver, lung, bone, and gut. Moreover, its roles include embryonic differentiation, trophoblast invasion of the uterine wall in early pregnancy, and fetal/neonate brain protection in hypoxic conditions. It is now recognized that activin A overexpression may be either cytostatic or mitogenic, depending on the cell type, with important implications for tumor biology. Activin A also regulates bone formation and regeneration, enhances joint inflammation in rheumatoid arthritis, and triggers pathogenic mechanisms in the respiratory system. In this 30-yr review, we analyze the evidence for physiological roles of activin A and the potential use of activin agonists and antagonists as therapeutic agents.

Fibrodysplasia Ossificans Progressiva (FOP): A Segmental Progeroid Syndrome

Segmental progeroid syndromes are commonly represented by genetic conditions which recapitulate aspects of physiological aging by similar, disparate, or unknown mechanisms. Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disease caused by mutations in the gene for ACVR1/ALK2 encoding Activin A receptor type I/Activin-like kinase 2, a bone morphogenetic protein (BMP) type I receptor, and results in the formation of extra-skeletal ossification and a constellation of others features, many of which resemble accelerated aging. The median estimated lifespan of individuals with FOP is approximately 56 years of age. Characteristics of precocious aging in FOP include both those that are related to dysregulated BMP signaling as well as those secondary to early immobilization. Progeroid features that may primarily be associated with mutations in ACVR1 include osteoarthritis, hearing loss, alopecia, subcutaneous lipodystrophy, myelination defects, heightened inflammation, menstrual abnormalities, and perhaps nephrolithiasis. Progeroid features that may secondarily be related to immobilization from progressive heterotopic ossification include decreased vital capacity, osteoporosis, fractures, sarcopenia, and predisposition to respiratory infections. Some manifestations of precocious aging may be attributed to both primary and secondary effects of FOP. At the level of lesion formation in FOP, soft tissue injury resulting in hypoxia, cell damage, and inflammation may lead to the accumulation of senescent cells as in aged tissue. Production of Activin A, platelet-derived growth factor, metalloproteinases, interleukin 6, and other inflammatory cytokines as part of the senescence-associated secretory phenotype could conceivably mediate the initial signaling cascade that results in the intense fibroproliferative response as well as the tissue-resident stem cell reprogramming leading up to ectopic endochondral bone formation. Consideration of FOP as a segmental progeroid syndrome offers a unique perspective into potential mechanisms of normal aging and may also provide insight for identification of new targets for therapeutic interventions in FOP.

Sulfasalazine treatment can cause a positive effect on LPS-induced endotoxic rats

The aim of this study, was to determine the effect of sulfasalazine for different periods of time reduces disseminated intravascular coagulation, inflammation and organ damages by inhibiting the nuclear factor kappa beta pathway. The study was performed with 30 Wistar albino rats and the groups were established as Control group, LPS group; endotoxemia was induced with LPS, SL5 group: sulfasalazine (300 mg/kg, single dose daily) was administered for 5 days before the LPS-induced endotoxemia, and LS group: sulfasalazine (300 mg/kg, single dose) was administered similtenously with LPS. Hemogram, biochemical, cytokine (IL-1β, IL-6, IL-10, TNF-α) and acute phase proteins (HPT, SAA, PGE2) analyzes and oxidative status values were measured from blood samples at 3 and 6 h after the last applications in the all groups. The rats were euthanized at 6 h and mRNA levels of BCL2 and BAX genes were examined from liver and brain tissues. Sulfasalazine reduced the increased IL-1β, IL-6, TNF-α and PGE₂ levels and significantly increased anti-inflammatory cytokine IL-10 levels. In addition, decreasing of ATIII level was prevented in the SL5 group, and decreasing of fibrinogen levels were prevented in the LS and SL5 groups within first 3 h. In LPS group, leukocyte and thrombocyte levels were decreased, however sulfasalazine application inhibited decreases of leukocyte levels in LS and SL5 groups. In addition, sulfasalazine inhibited the decrease of total antioxidant capacity and unchanged apoptosis in brain and liver. In conclusion, the use of sulfasalazine in different durations reduce the excessive inflammation of endotoxemia cases.

Systemic Activation of Activin A Signaling Causes Chronic Kidney Disease-Mineral Bone Disorder

The high cardiovascular mortality associated with chronic kidney disease (CKD) is caused in part by the CKD-mineral bone disorder (CKD-MBD) syndrome. The CKD-MBD consists of skeletal, vascular and cardiac pathology caused by metabolic derangements produced by kidney disease. The prevalence of osteopenia/osteoporosis resulting from the skeletal component of the CKD-MBD, renal osteodystrophy (ROD), in patients with CKD exceeds that of the general population and is a major public health concern. That CKD is associated with compromised bone health is widely accepted, yet the mechanisms underlying impaired bone metabolism in CKD are not fully understood. Therefore, clarification of the molecular mechanisms by which CKD produces ROD is of crucial significance. We have shown that activin A, a member of the transforming growth factor (TGF)-β super family, is an important positive regulator of receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis with Smad-mediated signaling being crucial for inducing osteoclast development and function. Recently, we have demonstrated systemic activation of activin receptors and activin A levels in CKD mouse models, such as diabetic CKD and Alport (AL) syndrome. In these CKD mouse models, bone remodeling caused by increased osteoclast numbers and activated osteoclastic bone resorption was observed and treatment with an activin receptor ligand trap repaired CKD-induced-osteoclastic bone resorption and stimulated individual osteoblastic bone formation, irrespective of parathyroid hormone (PTH) elevation. These findings have opened a new field for exploring mechanisms of activin A-enhanced osteoclast formation and function in CKD. Activin A appears to be a strong candidate for CKD-induced high-turnover ROD. Therefore, the treatment with the decoy receptor for activin A might be a good candidate for treatment for CKD-induced osteopenia or osteoporosis, indicating that the new findings from in these studies will lead to the identification of novel therapeutic targets for CKD-related and osteopenia and osteoporosis in general. In this review, we describe the impact of CKD-induced Smad signaling in osteoclasts, osteoblasts and vascular cells in CKD.

NF-κB pathways in the development and progression of colorectal cancer

Nuclear factor-κB (NF-κB) has been widely implicated in the development and progression of cancer. In colorectal cancer (CRC), NF-κB has a key role in cancer-related processes such as cell proliferation, apoptosis, angiogenesis, and metastasis. The role of NF-κB in CRC is complex, owed to the cross talk with other signaling pathways. Although there is sufficient evidence gained from cell lines and animal models that NF-κB is involved in cancer-related processes, because of a lack of studies in human tissue, the clinical evidence of its importance is limited in patients with CRC. This review summarizes evidence relating to how NF-κB is involved in the development and progression of CRC and comments on future work to be carried out.

A soluble activin type IIA receptor mitigates the loss of femoral neck bone strength and cancellous bone mass in a mouse model of disuse osteopenia

Disuse causes a rapid and substantial bone loss distinct in its pathophysiology from the bone loss associated with cancers, age, and menopause. While inhibitors of the activin-receptor signaling pathway (IASPs) have been shown to prevent ovariectomy- and cancer-induced bone loss, their application in a model of disuse osteopenia remains to be tested. Here, we show that a soluble activin type IIA receptor (ActRIIA-mFc) increases diaphyseal bone strength and cancellous bone mass, and mitigates the loss of femoral neck bone strength in the Botulinum Toxin A (BTX)-model of disuse osteopenia in female C57BL/6J mice. We show that ActRIIA-mFc treatment preferentially stimulates a dual-effect (anabolic-antiresorptive) on the periosteal envelope of diaphyseal bone, demonstrating in detail the effects of ActRIIA-mFc on cortical bone. These observations constitute a previously undescribed feature of IASPs that mediates at least part of their ability to mitigate detrimental effects of unloading on bone tissue. The study findings support the application of IASPs as a strategy to combat bone loss during disuse.

Platelet-rich plasma-induced feedback inhibition of activin A/follistatin signaling: A mechanism for tumor-low risk skin rejuvenation in irradiated rats

BACKGROUND

Platelet-rich plasma (PRP) is a source of natural growth factors and is emerging as a treatment modality to mitigate radiotherapy- induced adverse effects. Activin A (ACTA) is a member of the transforming growth factor-β (TGF-β) superfamily, which has been shown to modulate the inflammatory response and macrophages polarization between different phenotypes. The aim of this study is to determine the value of PRP in preventing radiation-induced malignancies in light of the cross-talk between PRP and activin A type II receptors (ActR-IIA)/follistatin (FST) signaling pathways where the inflammatory responses at 2 different time points were evaluated.

MATERIAL AND METHODS

Male albino rats were exposed to radiation and given PRP over the course of 6 days. Rats were sacrificed on day 7 or day 28 post radiation.

RESULTS

Quantitative real-time reverse transcriptase polymerase chain reaction (QRT-PCR) and western-blot showed that after 7 days of administrating of PRP, ActR-IIA/FST signaling was markedly induced and was associated with the expressions of inflammatory, natural killer and M1 macrophages markers, TNF-α, IL-1β, IFN-γ and IL-12. By contrast, on day 28 of PRP administration, ActR-IIA/FST signaling and the expressions of proinflammatory cytokines were downregulated in parallel with inducing M2 macrophages phenotype as indicated by arginase-1, IL-10 and dectin-1.

CONCLUSION

The suppression of inflammation and induction of M2 macrophages phenotype in response to PRP administration were found significantly linked to ActR-IIA/FST signaling downregulation. Furthermore, the specific M2 macrophage subtype was found to express dectin-1 receptors which have high affinity for tumor cells thereby is expected to reduce the potential for developing tumors after radiotherapy.

The Activin A-Peroxisome Proliferator-Activated Receptor Gamma Axis Contributes to the Transcriptome of GM-CSF-Conditioned Human Macrophages

GM-CSF promotes the functional maturation of lung alveolar macrophages (A-MØ), whose differentiation is dependent on the peroxisome proliferator-activated receptor gamma (PPARγ) transcription factor. In fact, blockade of GM-CSF-initiated signaling or deletion of the PPARγ-encoding gene PPARG leads to functionally defective A-MØ and the onset of pulmonary alveolar proteinosis. In vitro, macrophages generated in the presence of GM-CSF display potent proinflammatory, immunogenic and tumor growth-limiting activities. Since GM-CSF upregulates PPARγ expression, we hypothesized that PPARγ might contribute to the gene signature and functional profile of human GM-CSF-conditioned macrophages. To verify this hypothesis, PPARγ expression and activity was assessed in human monocyte-derived macrophages generated in the presence of GM-CSF [proinflammatory GM-CSF-conditioned human monocyte-derived macrophages (GM-MØ)] or M-CSF (anti-inflammatory M-MØ), as well as in ex vivo isolated human A-MØ. GM-MØ showed higher PPARγ expression than M-MØ, and the expression of PPARγ in GM-MØ was found to largely depend on activin A. Ligand-induced activation of PPARγ also resulted in distinct transcriptional and functional outcomes in GM-MØ and M-MØ. Moreover, and in the absence of exogenous activating ligands, PPARγ knockdown significantly altered the GM-MØ transcriptome, causing a global upregulation of proinflammatory genes and significantly modulating the expression of genes involved in cell proliferation and migration. Similar effects were observed in ex vivo isolated human A-MØ, where PPARγ silencing led to enhanced expression of genes coding for growth factors and chemokines and downregulation of cell surface pathogen receptors. Therefore, PPARγ shapes the transcriptome of GM-CSF-dependent human macrophages (in vitro derived GM-MØ and ex vivo isolated A-MØ) in the absence of exogenous activating ligands, and its expression is primarily regulated by activin A. These results suggest that activin A, through enhancement of PPARγ expression, help macrophages to switch from a proinflammatory to an anti-inflammatory polarization state, thus contributing to limit tissue damage and restore homeostasis.

Activin A inhibition attenuates sympathetic neural remodeling following myocardial infarction in rats

Inflammation serves a critical role in driving sympathetic neural remodeling following myocardial infarction (MI), and activin A has been implicated as an important mediator of the inflammatory response post-MI. However, whether activin A impacts sympathetic neural remodeling post-MI remains unclear. In the present study, the authors assessed the effects of activin A on sympathetic neural remodeling in a rat model of MI. Rats were randomly divided into sham, MI, and MI + follistatin-300 (FS, activin A inhibitor) groups. Cardiac tissues from the peri-infarct zone were assessed for expression of sympathetic neural remodeling and inflammatory factors in rats 4 weeks post-MI by western blotting and immunohistochemical methods. Heart function was assessed by echocardiography. It is demonstrated that FS administration significantly reduced post-MI upregulation of activin A, nerve growth factor protein lever, and the density of nerve fibers with positive and protein expression of sympathetic neural remodeling markers in nerve fibers, which included growth associated protein 43 and tyrosine hydroxylase. In addition, inhibition of activin A reduced cardiac inflammation post-MI based on the reduction of i) interleukin-1 and tumor necrosis factor-α protein expression, ii) numbers and/or proportional area of infiltrating macrophages and myofibroblasts and iii) phosphorylated levels of p65 and IκBα. Furthermore, activin A inhibition lessened heart dysfunction post-MI. These results suggested that activin A inhibition reduced sympathetic neural remodeling post-MI in part through inhibition of the inflammatory response. The current study implicates activin A as a potential therapeutic target to circumvent sympathetic neural remodeling post-MI.

Molecular targets of dietary phytochemicals for possible prevention and therapy of uterine fibroids: Focus on fibrosis

Uterine fibroids (myomas or leiomyomas) are common benign tumors of reproductive aged women. Fibroids are clinically apparent in 20-50% of women, and cause abnormal uterine bleeding, abdominal pain and discomfort, pregnancy complications and infertility. Unfortunately, limited numbers of medical treatment are available but no effective preventive strategies exist. Moreover, the benefits of medical treatments are tempered by lack of efficacy or serious adverse side effects. Fibrosis has recently been recognized as a key pathological event in leiomyoma development and growth. It is defined by the excessive deposition of extracellular matrix (ECM). ECM plays important role in making bulk structure of leiomyoma, and ECM-rich rigid structure is believed to be a cause of abnormal bleeding and pelvic pain/pressure. Dietary phytochemicals are known to regulate fibrotic process in different biological systems, and being considered as potential tool to manage human health. At present, very few dietary phytochemicals have been studied in uterine leiomyoma, and they are mostly known for their antiproliferative effects. Therefore, in this review, our aim was to introduce some dietary phytochemicals that could target fibrotic processes in leiomyoma. Thus, this review could serve as useful resource to develop antifibrotic drugs for possible prevention and treatment of uterine fibroids.

Role of Activins in Hepcidin Regulation during Malaria

Epidemiological observations have linked increased host iron with malaria susceptibility, and perturbed iron handling has been hypothesized to contribute to the potentially life-threatening anemia that may accompany blood-stage malaria infection. To improve our understanding of these relationships, we examined the pathways involved in regulation of the master controller of iron metabolism, the hormone hepcidin, in malaria infection. We show that hepcidin upregulation in Plasmodium berghei murine malaria infection was accompanied by changes in expression of bone morphogenetic protein (BMP)/sons of mothers against decapentaplegic (SMAD) pathway target genes, a key pathway involved in hepcidin regulation. We therefore investigated known agonists of the BMP/SMAD pathway and found that Bmp gene expression was not increased in infection. In contrast, activin B, which can signal through the BMP/SMAD pathway and has been associated with increased hepcidin during inflammation, was upregulated in the livers of Plasmodium berghei-infected mice; hepatic activin B was also upregulated at peak parasitemia during infection with Plasmodium chabaudi Concentrations of the closely related protein activin A increased in parallel with hepcidin in serum from malaria-naive volunteers infected in controlled human malaria infection (CHMI) clinical trials. However, antibody-mediated neutralization of activin activity during murine malaria infection did not affect hepcidin expression, suggesting that these proteins do not stimulate hepcidin upregulation directly. In conclusion, we present evidence that the BMP/SMAD signaling pathway is perturbed in malaria infection but that activins, although raised in malaria infection, may not have a critical role in hepcidin upregulation in this setting.

Inflammation-Stimulated Mesenchymal Stromal Cell-Derived Extracellular Vesicles Attenuate Inflammation

Extracellular vesicles (EVs) secreted by mesenchymal stromal cells (MSCs) have been proposed to be a key mechanistic link in the therapeutic efficacy of cells in response to cellular injuries through paracrine effects. We hypothesize that inflammatory stimulation of MSCs results in the release of EVs that have greater anti-inflammatory effects. The present study evaluates the immunomodulatory abilities of EVs derived from inflammation-stimulated and naive MSCs (MSCEv⁺ and MSCEv, respectively) isolated using a current Good Manufacturing Practice-compliant tangential flow filtration system. Detailed characterization of both EVs revealed differences in protein composition, cytokine profiles, and RNA content, despite similarities in size and expression of common surface markers. MSCEv⁺ further attenuated release of pro-inflammatory cytokines in vitro when compared to MSCEv, with a distinctly different pattern of EV-uptake by activated primary leukocyte subpopulations. The efficacy of EVs was partially attributed to COX2/PGE₂ expression. The present study demonstrates that inflammatory stimulation of MSCs renders release of EVs that have enhanced anti-inflammatory properties partially due to COX2/PGE₂ pathway alteration. Stem Cells 2018;36:79-90.

The emerging role of follistatin under stresses and its implications in diseases

Follistatin (FST), a single-chain glycosylated protein, is expressed in various tissues. The essential biological function of FST is binding and neutralizing transforming growth factor β (TGF-β) superfamily, including activin, myostatin, and bone morphogenetic protein (BMP). Emerging evidence indicates that FST also serves as a stress responsive protein, which plays a protective role under a variety of stresses. In most cases, FST performs the protective function through its neutralization of TGF-β superfamily. However, under certain circumstances, FST translocates into the nucleus to maintain cellular homeostasis independent of its extracellular antagonism activity. This review provides integrated insight into the most recent advances in understanding the role of FST under various stresses, and the clinical implications corresponding to these findings and discusses the mechanisms to be further studied.

Activin in acute pancreatitis: Potential risk-stratifying marker and novel therapeutic target

Acute Pancreatitis is a substantial health care challenge with increasing incidence. Patients who develop severe disease have considerable mortality. Currently, no reliable predictive marker to identify patients at risk for severe disease exists. Treatment is limited to rehydration and supporting care suggesting an urgent need to develop novel approaches to improve standard care. Activin is a critical modulator of inflammatory responses, but has not been assessed in pancreatitis. Here, we demonstrate that serum activin is elevated and strongly correlates with disease severity in two established murine models of acute pancreatitis induced by either cerulein or IL-12 + IL-18. Furthermore, in mice, inhibition of activin conveys survival benefits in pancreatitis. In addition, serum activin levels were measured from a retrospective clinical cohort of pancreatitis patients and high activin levels in patients at admission are predictive of worse outcomes, indicated by longer overall hospital and intensive care unit stays. Taken together, activin is a novel candidate as a clinical marker to identify those acute pancreatitis patients with severe disease who would benefit from aggressive treatment and activin may be a therapeutic target in severe acute pancreatitis.

Circulating Activin A predicts survival in cancer patients

BACKGROUND

Several experimental evidences pinpoint the possible role of Activin A (ActA) as a driver of cancer cachexia. Supporting this hypothesis, we showed recently that human cancer cachexia is associated with high ActA levels. Moreover, ActA levels were correlated with body weight loss and skeletal muscle density, two prognostic factors in cancer patients. Our goal was therefore to investigate the value of ActA to predict survival in cancer patients.

METHODS

Patients with colorectal or lung cancer were prospectively enrolled at the time of diagnosis or relapse between January 2012 and March 2014. At baseline, patients had clinical, nutritional, and functional assessment. Body composition and skeletal muscle density were measured by CT scan, and plasma ActA concentrations were determined. Overall survival (OS) was analysed since inclusion to 24 months later.

RESULTS

Survival data were available for 149 patients out of 152. Patients with high ActA (≥408 pg/mL) had lower OS than those with low levels, regardless the type of cancer (OS in colorectal cancer, 50% vs. 79%, P < 0.05; and in lung cancer, 27% vs. 67%, P = 0.001). The multivariable analysis confirmed the prognostic value of ActA independently of tumour stage or inflammatory markers, particularly in lung cancer. Low muscularity was also an independent prognostic factor.

CONCLUSIONS

Our study demonstrates that high ActA level is an independent prognosis factor of survival in cancer patients. More than a basic marker of the severity of the neoplastic disease or of the inflammatory process, ActA seems to influence survival by contributing to the development of cachexia and loss of skeletal muscle mass.

Activin signaling is an essential component of the TGF-β induced pro-metastatic phenotype in colorectal cancer

Advanced colorectal cancer (CRC) remains a critical health care challenge worldwide. Various TGF-β superfamily members are important in colorectal cancer metastasis, but their signaling effects and predictive value have only been assessed in isolation. Here, we examine cross-regulation and combined functions of the two most prominent TGF-β superfamily members activin and TGF-β in advanced colorectal cancer. In two clinical cohorts we observed by immune-based assay that combined serum and tissue activin and TGF-β ligand levels predicts outcome in CRC patients and is superior to single ligand assessment. While TGF-β growth suppression is independent of activin, TGF-β treatment leads to increased activin secretion in colon cancer cells and TGF-β induced cellular migration is dependent on activin, indicating pathway cross-regulation and functional interaction in vitro. mRNA expression of activin and TGF-β pathway members were queried in silico using the TCGA data set. Coordinated ligand and receptor expression is common in solid tumors for activin and TGF-β pathway members. In conclusion, activin and TGF-β are strongly connected signaling pathways that are important in advanced CRC. Assessing activin and TGF-β signaling as a unit yields important insights applicable to future diagnostic and therapeutic interventions.

Soluble activin type IIB receptor improves fracture healing in a closed tibial fracture mouse model

Fractures still present a significant burden to patients due to pain and periods of unproductivity. Numerous growth factors have been identified to regulate bone remodeling. However, to date, only the bone morphogenetic proteins (BMPs) are used to enhance fracture healing in clinical settings. Activins are pleiotropic growth factors belonging to the TGF-β superfamily. We and others have recently shown that treatment with recombinant fusion proteins of activin receptors greatly increases bone mass in different animal models by trapping activins and other ligands thus inhibiting their signaling pathways. However, their effects on fracture healing are less known. Twelve-week old male C57Bl mice were subjected to a standardized, closed tibial fracture model. Animals were divided into control and treatment groups and were administered either PBS control or a soluble activin type IIB receptor (ActRIIB-Fc) intraperitoneally once a week for a duration of two or four weeks. There were no significant differences between the groups at two weeks but we observed a significant increase in callus mineralization in ActRIIB-Fc-treated animals by microcomputed tomography imaging at four weeks. Bone volume per tissue volume was 60%, trabecular number 55% and bone mineral density 60% higher in the 4-week calluses of the ActRIIB-Fc-treated mice (p<0.05 in all). Biomechanical strength of 4-week calluses was also significantly improved by ActRIIB-Fc treatment as stiffness increased by 64% and maximum force by 45% (p<0.05) compared to the PBS-injected controls. These results demonstrate that ActRIIB-Fc treatment significantly improves healing of closed long bone fractures. Our findings support the previous reports of activin receptors increasing bone mass but also demonstrate a novel approach for using ActRIIB-Fc to enhance fracture healing.

Hyperglycemia is associated with reduced testicular function and activin dysregulation in the Ins2Akita+/- mouse model of type 1 diabetes

Type 1 diabetes (T1D) is associated with subfertility in men. We hypothesised that this results from inhibitory effects of chronic hyperglycemia on testicular function and used the Ins2^Akita+/- mouse model to investigate this. Diabetic mice exhibited progressive testicular dysfunction, with a 30% reduction in testis weight at 24 weeks of age. Diabetic mice showed significantly reduced seminiferous tubule diameters and increased spermatogenic disruption, although testes morphology appeared grossly normal. Unexpectedly, serum LH and intra-testicular testosterone were similar in all groups. Ins2^Akita+/- mice displayed elevation of the testicular inflammatory cytokines activin A and IL-6. Intratesticular activin B was downregulated, while the activin regulatory proteins, follistatin and inhibin, were unchanged. Activin signalling, measured by pSmad3 and Smad4 production, was enhanced in diabetic mice only. These results suggest that prolonged exposure to hyperglycemia in the Ins2^Akita+/- mice leads to progressive testicular disruption mediated by testicular activin activity, rather than hormonal dysregulation.

Follistatin and the Breast Implant Capsule

Supplemental Digital Content is available in the text.

Background:

Breast capsular contracture remains an elusive problem faced by plastic surgeons and is the leading long-term complication after breast implantation. Follistatin (Fst) is a protein with known anti-inflammatory and antifibrotic properties and has the potential to limit the severity of diseases associated with inflammation and fibrosis such as capsular contracture. The aim of this study was to examine the effect of Fst288 on capsular fibrosis around silicone implants in a mouse model.

Methods:

BALB/c mice were implanted subcutaneously with untreated silicone implants (baseline control). In the experimental group, immediately after silicone implant insertion, the implant pocket received either a single injection of 1 µg Fst288 or normal saline (internal control). The animals were killed at 3, 5, 7, 14, 28, and 90 days after surgery, and serum, implants, and the surrounding tissue were removed for histological and immunohistochemical analyses.

Results:

Fst288 treatment resulted in significant decreases in capsule thickness at 28 days (P < 0.05) and 3 months (P < 0.001), decreased collagen production at 14 days (P < 0.05) and 3 months (P < 0.01), decreased angiogenesis at 3 months (P < 0.001), decreased α-smooth muscle actin levels at 3 months (P < 0.05), and a decrease in the number of CD45+ cells at days 5 (P < 0.05) and 7 (P < 0.01), respectively, when compared with control implants.

Conclusions:

A single injection of Fst288 at the time of silicone implant insertion into the mice results in a significant reduction in pericapsular inflammation and capsular fibrosis.

Unexpected and striking effect of heparin-free dialysis on cytokine release

Heparin (both unfractionated and low molecular weight) is not only a potent anticoagulant but also has many pleiotropic effects, some of which are mediated by cytokine release. We compared the effect of hemodialysis (HD) with enoxaparin as an anticoagulant and without systemic anticoagulation (heparin-grafted membrane—Evodial) on the release of monocyte chemoattractant protein 1 (MCP-1), endostatin (ES) and activin A (Act-A). Nineteen stable HD patients were dialyzed with or without heparin, and plasma levels of MCP-1, ES and Act-A were measured after such a dialysis. During HD with Evodial, the intradialytic levels of all three cytokines were 2–3 folds lower. The between-anticoagulant differences were significant over time for all three cytokines: MCP-1 (P < 0.001), ES (P < 0.001) and Act-A (P < 0.001). This striking effect of heparin-free dialysis with Evodial membrane may be beneficial not only because it reduces the possibility of bleeding complications but also because it might reduce proinflammatory cytokine concentration and therefore contribute to the improvement in endothelial function. Further studies are needed to determine whether it has a positive effect on morbidity and mortality of maintenance HD patients.

Activin A induces skeletal muscle catabolism via p38β mitogen-activated protein kinase

BACKGROUND

Activation of type IIB activin receptor (ActRIIB) in skeletal muscle leads to muscle atrophy because of increased muscle protein degradation. However, the intracellular signalling mechanism that mediates ActRIIB-activated muscle catabolism is poorly defined.

METHODS

We investigated the role of p38β mitogen-activated protein kinases (MAPK) in mediating ActRIIB ligand activin A-activated muscle catabolic pathways in C2C12 myotubes and in mice with perturbation of this kinase pharmacologically and genetically.

RESULTS

Treatment of C2C12 myotubes with activin A or myostatin rapidly activated p38 MAPK and its effector C/EBPβ within 1 h. Paradoxically, Akt was activated at the same time through a p38 MAPK-independent mechanism. These events were followed by up-regulation of ubiquitin ligases atrogin1 (MAFbx) and UBR2 (E3α-II), as well as increase in LC3-II, a marker of autophagosome formation, leading to myofibrillar protein loss and myotube atrophy. The catabolic effects of activin A were abolished by p38α/β MAPK inhibitor SB202190. Using small interfering RNA-mediated gene knockdown, we found that the catabolic activity of activin A was dependent on p38β MAPK specifically. Importantly, systemic administration of activin A to mice similarly activated the catabolic pathways in vivo, and this effect was blocked by SB202190. Further, activin A failed to activate the catabolic pathways in mice with muscle-specific knockout of p38β MAPK. Interestingly, activin A up-regulated MuRF1 in a p38 MAPK-independent manner, and MuRF1 did not appear responsible for activin A-induced myosin heavy chain loss and muscle atrophy.

CONCLUSIONS

ActRIIB-mediated activation of muscle catabolism is dependent on p38β MAPK-activated signalling.

Follistatin attenuates radiation-induced fibrosis in a murine model

Purpose

Fibrosis can be a disabling, severe side effect of radiotherapy that can occur in patients, and for which there is currently no effective treatment. The activins, proteins which are members of the TGFβ superfamily, have a major role in stimulating the inflammatory response and subsequent fibrosis. Follistatin is an endogenous protein that binds the activins virtually irreversibly and inhibits their actions. These studies test if follistatin can attenuate the fibrotic response using a murine model of radiation-induced fibrosis.

Experimental design

C57BL/6 mice were subcutaneously injected with follistatin 24 hours prior to irradiation. Mice were irradiated in a 10 x 10 mm square area of the right hind leg with 35 Gy and were given follistatin 24 hours before radiation and three times a week for six months following. Leg extension was measured, and tissue was collected for histological and molecular analysis to evaluate the progression of the radiation-induced fibrosis.

Results

Leg extension was improved in follistatin treated mice compared to vehicle treated mice at six months after irradiation. Also, epidermal thickness and cell nucleus area of keratinocytes were decreased by the follistatin treatment compared to the cells in irradiated skin of control mice. Finally, the gene expression of transforming growth factor β1 (Tgfb1), and smooth muscle actin (Acta2) were decreased in the irradiated skin and Acta2 and inhibin βA subunit (Inhba) were decreased in the irradiated muscle of the follistatin treated mice.

Conclusions

Follistatin attenuated the radiation-induced fibrotic response in irradiated mice. These studies provide the data to support further investigation of the use of follistatin to reduce radiation-induced fibrosis in patients undergoing radiotherapy for cancer.