Neutrophil-derived Activin-A moderates their pro-NETotic activity and attenuates collateral tissue damage caused by Influenza A virus infection

Background

Pre-neutrophils, while developing in the bone marrow, transcribe the Inhba gene and synthesize Activin-A protein, which they store and release at the earliest stage of their activation in the periphery. However, the role of neutrophil-derived Activin-A is not completely understood.

Methods

To address this issue, we developed a neutrophil-specific Activin-A-deficient animal model (S100a8-Cre/Inhba fl/fl mice) and analyzed the immune response to Influenza A virus (IAV) infection. More specifically, evaluation of body weight and lung mechanics, molecular and cellular analyses of bronchoalveolar lavage fluids, flow cytometry and cell sorting of lung cells, as well as histopathological analysis of lung tissues, were performed in PBS-treated and IAV-infected transgenic animals.

Results

We found that neutrophil-specific Activin-A deficiency led to exacerbated pulmonary inflammation and widespread hemorrhagic histopathology in the lungs of IAV-infected animals that was associated with an exuberant production of neutrophil extracellular traps (NETs). Moreover, deletion of the Activin-A receptor ALK4/ACVR1B in neutrophils exacerbated IAV-induced pathology as well, suggesting that neutrophils themselves are potential targets of Activin-A-mediated signaling. The pro-NETotic tendency of Activin-A-deficient neutrophils was further verified in the context of thioglycollate-induced peritonitis, a model characterized by robust peritoneal neutrophilia. Of importance, transcriptome analysis of Activin-A-deficient neutrophils revealed alterations consistent with a predisposition for NET release.

Conclusion

Collectively, our data demonstrate that Activin-A, secreted by neutrophils upon their activation in the periphery, acts as a feedback mechanism to moderate their pro-NETotic tendency and limit the collateral tissue damage caused by neutrophil excess activation during the inflammatory response.

Coordinated activation of TGF-β and BMP pathways promotes autophagy and limits liver injury after acetaminophen intoxication

Ligands of the transforming growth factor-β (TGF-β) superfamily, including TGF-βs, activins, and bone morphogenetic proteins (BMPs), have been implicated in hepatic development, homeostasis, and pathophysiology. We explored the mechanisms by which hepatocytes decode and integrate injury-induced signaling from TGF-βs and activins (TGF-β/Activin) and BMPs. We mapped the spatiotemporal patterns of pathway activation during liver injury induced by acetaminophen (APAP) in dual reporter mice carrying a fluorescent reporter of TGF-β/Activin signaling and a fluorescent reporter of BMP signaling. APAP intoxication induced the expression of both reporters in a zone of cells near areas of tissue damage, which showed an increase in autophagy and demarcated the borders between healthy and injured tissues. Inhibition of TGF-β superfamily signaling by overexpressing the inhibitor Smad7 exacerbated acute liver histopathology but eventually accelerated tissue recovery. Transcriptomic analysis identified autophagy as a process stimulated by TGF-β1 and BMP4 in hepatocytes, with Trp53inp2, which encodes a rate-limiting factor for autophagy initiation, as the most highly induced autophagy-related gene. Collectively, these findings illustrate the functional interconnectivity of the TGF-β superfamily signaling system, implicate the coordinated activation of TGF-β/Activin and BMP pathways in balancing tissue reparatory and regenerative processes upon APAP-induced hepatotoxicity, and highlight opportunities and potential risks associated with targeting this signaling system for treating hepatic diseases.

The Activin/Follistatin Axis Is Severely Deregulated in COVID-19 and Independently Associated With In-Hospital Mortality

Background

Activins are members of the TGFβ-superfamily implicated in the pathogenesis of several immuno-inflammatory disorders. Based on our previous studies demonstrating that over-expression of Activin-A in murine lung causes pathology sharing key features of COVID-19, we hypothesized that Activins and their natural inhibitor Follistatin might be particularly relevant to COVID-19 pathophysiology.

Methods

Activin-A, Activin-B and Follistatin levels were retrospectively analyzed in 574 serum samples from 263 COVID-19 patients hospitalized in three independent centers, and compared with common demographic, clinical and laboratory parameters. Optimal-scaling with ridge-regression was used to screen variables and establish a prediction model.

Result

The Activin/Follistatin-axis was significantly deregulated during the course of COVID-19, correlated with severity and independently associated with mortality. FACT-CLINYCoD, a novel disease scoring system, adding one point for each of Follistatin>6235pg/ml, Activin-A>591pg/ml, Activin-B>249pg/ml, CRP>10.3mg/dL, LDH>427U/L, Intensive Care Unit (ICU) admission, Neutrophil/Lymphocyte-Ratio>5.6, Age>61, Comorbidities>1 and D-dimers>1097ng/ml, efficiently predicted fatal outcome in an initial cohort (AUC: 0.951; 95%CI: 0.919-0.983, p<10 ^-6). Two independent cohorts that were used for validation indicated similar AUC values.

Conclusions

This study unravels strong link between Activin/Follistatin-axis and COVID-19 mortality and introduces FACT-CLINYCoD, a novel pathophysiology-based tool that allows dynamic prediction of disease outcome, supporting clinical decision making.

Activation of both transforming growth factor-β and bone morphogenetic protein signalling pathways upon traumatic brain injury restrains pro-inflammatory and boosts tissue reparatory responses of reactive astrocytes and microglia

Various ligands and receptors of the transforming growth factor-β superfamily have been found upregulated following traumatic brain injury; however, the role of this signalling system in brain injury pathophysiology is not fully characterized. To address this, we utilized an acute stab wound brain injury model to demonstrate that hallmarks of transforming growth factor-β superfamily system activation, such as levels of phosphorylated Smads, ligands and target genes for both transforming growth factor-β and bone morphogenetic protein pathways, were upregulated within injured tissues. Using a bone morphogenetic protein-responsive reporter mouse model, we showed that activation of the bone morphogenetic protein signalling pathway involves primarily astrocytes that demarcate the wound area. Insights regarding the potential role of transforming growth factor-β superfamily activation in glia cells within the injured tissues were obtained indirectly by treating purified reactive astrocytes and microglia with bone morphogenetic protein-4 or transforming growth factor-β1 and characterizing changes in their transcriptional profiles. Astrocytes responded to both ligands with considerably overlapping profiles, whereas, microglia responded selectively to transforming growth factor-β1. Novel pathways, crucial for repair of tissue-injury and blood-brain barrier, such as activation of cholesterol biosynthesis and transport, production of axonal guidance and extracellular matrix components were upregulated by transforming growth factor-β1 and/or bone morphogenetic protein-4 in astrocytes. Moreover, both ligands in astrocytes and transforming growth factor-β1 in microglia shifted the phenotype of reactive glia cells towards the anti-inflammatory and tissue reparatory 'A2'-like and 'M0/M2'-like phenotypes, respectively. Increased expression of selected key components of the in vitro modulated pathways and markers of 'A2'-like astrocytes was confirmed within the wound area, suggesting that these processes could also be modulated in situ by the integrated action of transforming growth factor-β and/or bone morphogenetic protein-mediated signalling. Collectively, our study provides a comprehensive comparative analysis of transforming growth factor-β superfamily signalling in reactive astrocytes and microglia and points towards a crucial role of both transforming growth factor-β and bone morphogenetic protein pathways in modulating the inflammatory and brain injury reparatory functions of activated glia cells.

PI3K/AKT pathway genetic alterations and dysregulation of expression in bladder cancer

PURPOSE

To examine the involvement of specific components of the PI3K/AKT pathway in urinary bladder cancer development.

METHODS

Samples from 65 tumors and 13 normal bladder tissues were collected. Genomic DNA isolation from snap-frozen and paraffin-embedded laser-microdissected tissues was followed by Sanger sequencing, whereas total RNA was purified for use in RT-PCR analyses. Immunohistochemistry was carried out on sections of paraffin-embedded biopsy material.

RESULTS

Three pathogenic mutations (two missense and one frameshift) were identified in exon 20 of PIK3CA {c.3140A>G (p.His1047Arg), c.[3172A>T(;)3174C>T] (p.lle1058Phe), c.3203dupA (p.Asn1068Lysfs*5)} after laser capture microdissection, whereas PTEN mRNA expression was found to be downregulated in bladder cancer tissues compared to normal bladder urothelium. Upregulation of cytoplasmic and nuclear p-AKT expression was detected in low grade tumors, whereas in infiltrating carcinomas p-AKT was shown to be downregulated and confined to the cytoplasm. PTEN expression was weak and mainly cytoplasmic in superficial tumors, but stronger and nuclear in the infiltrating tumors.

CONCLUSIONS

PI3K/AKT pathway activation is crucial for bladder cancer initiation and progression. In this context, PIK3CA, p-AKT and nuclear PTEN could be used along with other biomarkers for prognosis and selection of appropriate therapy in the clinical management of bladder cancer.

Toll-Like Receptor 7 Protects From Atherosclerosis by Constraining “Inflammatory” Macrophage Activation

Background

Toll-like receptors (TLRs) have long been considered to be major culprits in the development of atherosclerosis, contributing both to its progression and clinical complications. However, evidence for most TLRs beyond TLR2 and TLR4 is lacking.

Methods and Results

We used experimental mouse models, human atheroma cultures, and well-established human biobanks to investigate the role of TLR7 in atherosclerosis. We report the unexpected finding that TLR7, a receptor recognizing self–nucleic acid complexes, is protective in atherosclerosis. In Apoe −/− mice, functional inactivation of TLR7 resulted in accelerated lesion development, increased stenosis, and enhanced plaque vulnerability as revealed by Doppler ultrasound and/or histopathology. Mechanistically, TLR7 interfered with macrophage proinflammatory responses to TLR2 and TLR4 ligands, reduced monocyte chemoattractant protein-1 production, and prevented expansion of Ly6C hi inflammatory monocytes and accumulation of inflammatory M1 macrophages into developing atherosclerotic lesions. In human carotid endarterectomy specimens TLR7 levels were consistently associated with an M2 anti-inflammatory macrophage signature (interleukin [IL]-10, IL-1RA, CD163, scavenger and C-type lectin receptors) and collagen genes, whereas they were inversely related or unrelated to proinflammatory mediators (IL-12/IL-23, interferon beta, interferon gamma, CD40L) and platelet markers. Moreover, in human atheroma cultures, TLR7 activation selectively suppressed the production of key proatherogenic factors such as monocyte chemoattractant protein-1 and tumor necrosis factor without affecting IL-10.

Conclusions

These findings provide evidence for a beneficial role of TLR7 in atherosclerosis by constraining inflammatory macrophage activation and cytokine production. This challenges the prevailing concept that all TLRs are pathogenic and supports the exploitation of the TLR7 pathway for therapy.

Variation in trace element contents among chicken, turkey, duck, goose, and pigeon eggs analyzed by inductively coupled plasma mass spectrometry (ICP-MS)

Despite substantial interest in the trace element content of eggs by poultry breeders, nutritionists, and environmental scientists, available data about trace elements levels in eggs are scarce. Trace element contents in yolk and albumen of chicken, turkey, duck, goose, and pigeon eggs were analyzed to establish a baseline dataset and assess differences among trace element content in avian species. We measured the selenium (Se), zinc (Zn), manganese (Mn), cobalt (Co), copper (Cu), molybdenum (Mo), vanadium (V), chromium (Cr), nickel (Ni), arsenic (As), cadmium (Cd), and thallium (Tl) contents in both yolk and albumen by inductively coupled plasma mass spectrometry. One hundred twenty eggs deriving from 24 birds of each species, reared in the same poultry farm in northern Greece, were used; bird feed was common and based on cereals and legumes and contained no added vitamins or microminerals. Trace element contents in yolks were far higher than those in albumen, except for V and Ni. In yolks, the highest content for Se, Mo, and Tl were in pigeon eggs, for Zn, Mn, Cu, and Cr in turkey eggs, and for Co and Ni in goose eggs. In albumen, Se was highest in duck eggs, while Zn, Mn, and Co in pigeon ones. It is concluded that there is a substantial, up to threefold, variation for trace element contents in eggs among different domestic avian species offered the same feed.

Immunoelectron study of somatostatin, gastrin and glucagon in human colorectal adenocarcinomas and liver metastases

The aim of this study was to investigate the role and function of somatostatin, glucagon and gastrin in 35 colorectal adenocarcinoma and 25 liver metastases. The investigation was carried out at the electron immunocytochemistry level. Our results showed that well-differentiated tissues have the highest somatostatin levels compared to poorly-differentiated tumors while glucagon levels remain high. We also found gastrin immunoreactivity in cell membranes of poorly-differentiated primary adenocarcinoma tissues and in liver metastases. Low somatostatin expression, high glucagon expression and the presence of gastrin were found in tumors of poor grading and therefore poor prognosis.