Impact of disrupted cyclic stretch in intracranial aneurysms: Insights from endothelial cell transcriptomic dataset.

Intracranial aneurysm (IA) rupture is a common cause of hemorrhagic stroke. The treatment of unruptured IAs is a challenging decision that requires delicate risk stratification. The rate of poor clinical outcomes after surgical intervention (aneurysm clipping) or endovascular coiling remains elevated (6.7% and 4.8%, respectively), and they do not provide an absolute guarantee to prevent IA growth and rupture. Currently, there is no pharmaceutical treatment to cure or stabilize IAs. Improving the current or developing new treatments for IA disease would require a better understanding of the cellular and molecular mechanisms occurring in the different stages of the disease. Hemodynamic forces play a critical role in IA disease. While the role of wall shear stress in IAs is well-established, the influence of cyclic circumferential stretch (CCS) still needs clarification. IAs are generally characterized by a lack of CCS. In this investigation, we sought to understand the effect of aneurysmal CCS on endothelial cell (EC) function and its potential significance in IA disease, hypothesizing that CCS can influence IA wall remodelling. RNA-seq data were generated from human umbilical vein ECs (HUVECs) exposed to physiological (6%) or aneurysmal CCS (static). We performed differential gene expression and pathway enrichment analysis. Additionally, we highlighted cell junction gene expression between static and 6% CCS to contribute to the debate about how cell junctions affect endothelium stability and integrity. Researchers in the vascular biology field may benefit from this transcriptomic profile to understand the effect of mechanical stretch on EC biology and its potential significance in vascular disease development.

C-type lectin receptor agonists elicit functional IL21-expressing Tfh cells and induce primary B cell responses in neonates.

Introduction: C-type lectin receptor (CLR) agonists emerged as superior inducers of primary B cell responses in early life compared with Toll-like receptor (TLR) agonists, while both types of adjuvants are potent in adults. Methods: Here, we explored the mechanisms accounting for the differences in neonatal adjuvanticity between a CLR-based (CAF®01) and a TLR4-based (GLA-SE) adjuvant administered with influenza hemagglutinin (HA) in neonatal mice, by using transcriptomics and systems biology analyses. Results: On day 7 after immunization, HA/CAF01 increased IL6 and IL21 levels in the draining lymph nodes, while HA/GLA-SE increased IL10. CAF01 induced mixed Th1/Th17 neonatal responses while T cell responses induced by GLA-SE had a more pronounced Th2-profile. Only CAF01 induced T follicular helper (Tfh) cells expressing high levels of IL21 similar to levels induced in adult mice, which is essential for germinal center (GC) formation. Accordingly, only CAF01- induced neonatal Tfh cells activated adoptively transferred hen egg lysozyme (HEL)-specific B cells to form HEL+ GC B cells in neonatal mice upon vaccination with HEL-OVA. Discussion: Collectively, the data show that CLR-based adjuvants are promising neonatal and infant adjuvants due to their ability to harness Tfh responses in early life.

Genetic knockout of NTRK2 by CRISPR/Cas9 decreases neurogenesis and favors glial progenitors during differentiation of neural progenitor stem cells.

The tropomyosin receptor kinase B (TrkB) is encoded by the NTRK2 gene. It belongs to the family of transmembrane tyrosine kinases, which have key roles in the development and maintenance of the nervous system. Brain-derived neurotrophic factor (BDNF) and the neurotrophins NT3 and NT4/5 have high affinity for TrkB. Dysregulation of TrkB is associated to a large spectrum of diseases including neurodegeneration, psychiatric diseases and some cancers. The function of TrkB and its role in neural development have mainly been decrypted using transgenic mouse models, pharmacological modulators and human neuronal cell lines overexpressing NTRK2. In this study, we identified high expression and robust activity of TrkB in ReNcell VM, an immortalized human neural progenitor stem cell line and generated NTRK2-deficient (NTRK2-/-) ReNcell VM using the CRISPR/Cas9 gene editing technology. Global transcriptomic analysis revealed major changes in expression of specific genes responsible for neurogenesis, neuronal development and glial differentiation. In particular, key neurogenic transcription factors were massively down-regulated in NTRK2-/- cells, while early glial progenitor markers were enriched in NTRK2-/- cells compared to NTRK2+/+. This indicates a previously undescribed inhibitory role of TrkB on glial differentiation in addition to its well-described pro-neurogenesis role. Altogether, we have generated for the first time a human neural cell line with a loss-of-function mutation of NTRK2, which represents a reproducible and readily available cell culture system to study the role of TrkB during human neural differentiation, analyze the role of TrkB isoforms as well as validate TrkB antibodies and pharmacological agents targeting the TrkB pathway.

Refined innate plasma signature after rVSVΔG-ZEBOV-GP immunization is shared among adult cohorts in Europe and North America.

Background: During the last decade Ebola virus has caused several outbreaks in Africa. The recombinant vesicular stomatitis virus-vectored Zaire Ebola (rVSVΔG-ZEBOV-GP) vaccine has proved safe and immunogenic but is reactogenic. We previously identified the first innate plasma signature response after vaccination in Geneva as composed of five monocyte-related biomarkers peaking at day 1 post-immunization that correlates with adverse events, biological outcomes (haematological changes and viremia) and antibody titers. In this follow-up study, we sought to identify additional biomarkers in the same Geneva cohort and validate those identified markers in a US cohort. Methods: Additional biomarkers were identified using multiplexed protein biomarker platform O-link and confirmed by Luminex. Principal component analysis (PCA) evaluated if these markers could explain a higher variability of the vaccine response (and thereby refined the initial signature). Multivariable and linear regression models evaluated the correlations of the main components with adverse events, biological outcomes, and antibody titers. External validation of the refined signature was conducted in a second cohort of US vaccinees (n=142). Results: Eleven additional biomarkers peaked at day 1 post-immunization: MCP2, MCP3, MCP4, CXCL10, OSM, CX3CL1, MCSF, CXCL11, TRAIL, RANKL and IL15. PCA analysis retained three principal components (PC) that accounted for 79% of the vaccine response variability. PC1 and PC2 were very robust and had different biomarkers that contributed to their variability. PC1 better discriminated different doses, better defined the risk of fever and myalgia, while PC2 better defined the risk of headache. We also found new biomarkers that correlated with reactogenicity, including transient arthritis (MCP-2, CXCL10, CXCL11, CX3CL1, MCSF, IL-15, OSM). Several innate biomarkers are associated with antibody levels one and six months after vaccination. Refined PC1 correlated strongly in both data sets (Geneva: r = 0.97, P < 0.001; US: r = 0.99, P< 0.001). Conclusion: Eleven additional biomarkers refined the previously found 5-biomarker Geneva signature. The refined signature better discriminated between different doses, was strongly associated with the risk of adverse events and with antibody responses and was validated in a separate cohort.

Transcriptomic Analysis of E. coli after Exposure to a Sublethal Concentration of Hydrogen Peroxide Revealed a Coordinated Up-Regulation of the Cysteine Biosynthesis Pathway.

Hydrogen peroxide (H2O2) is a key defense component of host-microbe interaction. However, H2O2 concentrations generated by immune cells or epithelia are usually insufficient for bacterial killing and rather modulate bacterial responses. Here, we investigated the impact of sublethal H2O2 concentration on gene expression of E. coli BW25113 after 10 and 60 min of exposure. RNA-seq analysis revealed that approximately 12% of bacterial genes were strongly dysregulated 10 min following exposure to 2.5 mM H2O2. H2O2 exposure led to the activation of a specific antioxidant response and a general stress response. The latter was characterized by a transient down-regulation of genes involved in general metabolism, such as nucleic acid biosynthesis and translation, with a striking and coordinated down-regulation of genes involved in ribosome formation, and a sustained up-regulation of the SOS response. We confirmed the rapid transient and specific response mediated by the transcription factor OxyR leading to up-regulation of antioxidant systems, including the catalase-encoding gene (katG), that rapidly degrade extracellular H2O2 and promote bacterial survival. We documented a strong and transient up-regulation of genes involved in sulfur metabolism and cysteine biosynthesis, which are under the control of the transcription factor CysB. This strong specific transcriptional response to H2O2 exposure had no apparent impact on bacterial survival, but possibly replenishes the stores of oxidized cysteine and glutathione. In summary, our results demonstrate that different stress response mechanisms are activated by H2O2 exposure and highlight the cysteine synthesis as an antioxidant response in E. coli.

Tissue-resident memory CD8+ T cells cooperate with CD4+ T cells to drive compartmentalized immunopathology in the CNS.

In chronic inflammatory diseases of the central nervous system (CNS), immune cells persisting behind the blood-brain barrier are supposed to promulgate local tissue destruction. The drivers of such compartmentalized inflammation remain unclear, but tissue-resident memory T cells (TRM) represent a potentially important cellular player in this process. Here, we investigated whether resting CD8+ TRM persisting after cleared infection with attenuated lymphocytic choriomeningitis virus (LCMV) can initiate immune responses directed against cognate self-antigen in the CNS. We demonstrated that time-delayed conditional expression of the LCMV glycoprotein as neo-self-antigen by glia cells reactivated CD8+ TRM. Subsequently, CD8+ TRM expanded and initiated CNS inflammation and immunopathology in an organ-autonomous manner independently of circulating CD8+ T cells. However, in the absence of CD4+ T cells, TCF-1+ CD8+ TRM failed to expand and differentiate into terminal effectors. Similarly, in human demyelinating CNS autoimmune lesions, we found CD8+ T cells expressing TCF-1 that predominantly exhibited a TRM-like phenotype. Together, our study provides evidence for CD8+ TRM-driven CNS immunopathology and sheds light on why inflammatory processes may evade current immunomodulatory treatments in chronic autoimmune CNS conditions.

Neutralization of S100A4 induces stabilization of atherosclerotic plaques: role of smooth muscle cells.

AIMS: During atherosclerosis, smooth muscle cells (SMCs) accumulate in the intima where they switch from a contractile to a synthetic phenotype. From porcine coronary artery, we isolated spindle-shaped (S) SMCs exhibiting features of the contractile phenotype and rhomboid (R) SMCs typical of the synthetic phenotype. S100A4 was identified as a marker of R-SMCs in vitro and intimal SMCs, in pig and man. S100A4 exhibits intra- and extracellular functions. In this study, we investigated the role of extracellular S100A4 in SMC phenotypic transition. METHODS AND RESULTS: S-SMCs were treated with oligomeric recombinant S100A4 (oS100A4), which induced nuclear factor (NF)-κB activation. Treatment of S-SMCs with oS100A4 in combination with platelet-derived growth factor (PDGF)-BB induced a complete SMC transition towards a pro-inflammatory R-phenotype associated with NF-κB activation, through toll-like receptor-4. RNA sequencing of cells treated with oS100A4/PDGF-BB revealed a strong up-regulation of pro-inflammatory genes and enrichment of transcription factor binding sites essential for SMC phenotypic transition. In a mouse model of established atherosclerosis, neutralization of extracellular S100A4 decreased area of atherosclerotic lesions, necrotic core, and CD68 expression and increased α-smooth muscle actin and smooth muscle myosin heavy chain expression. CONCLUSION: We suggest that the neutralization of extracellular S100A4 promotes the stabilization of atherosclerotic plaques. Extracellular S100A4 could be a new target to influence the evolution of atherosclerotic plaques.

Primary cilia control endothelial permeability by regulating expression and location of junction proteins.

AIMS: Wall shear stress (WSS) determines intracranial aneurysm (IA) development. Polycystic kidney disease (PKD) patients have a high IA incidence and risk of rupture. Dysfunction/absence of primary cilia in PKD endothelial cells (ECs) may impair mechano-transduction of WSS and favour vascular disorders. The molecular links between primary cilia dysfunction and IAs are unknown. METHODS AND RESULTS: Wild-type and primary cilia-deficient Tg737orpk/orpk arterial ECs were submitted to physiological (30 dynes/cm2) or aneurysmal (2 dynes/cm2) WSS, and unbiased transcriptomics were performed. Tg737orpk/orpk ECs displayed a fivefold increase in the number of WSS-responsive genes compared to wild-type cells. Moreover, we observed a lower trans-endothelial resistance and a higher endothelial permeability, which correlated with disorganized intercellular junctions in Tg737orpk/orpk cells. We identified ZO-1 as a central regulator of primary cilia-dependent endothelial junction integrity. Finally, clinical and histological characteristics of IAs from non-PKD and PKD patients were analysed. IAs in PKD patients were more frequently located in the middle cerebral artery (MCA) territory than in non-PKD patients. IA domes from the MCA of PKD patients appeared thinner with less collagen and reduced endothelial ZO-1 compared with IA domes from non-PKD patients. CONCLUSION: Primary cilia dampen the endothelial response to aneurysmal low WSS. In absence of primary cilia, ZO-1 expression levels are reduced, which disorganizes intercellular junctions resulting in increased endothelial permeability. This altered endothelial function may not only contribute to the severity of IA disease observed in PKD patients, but may also serve as a potential diagnostic tool to determine the vulnerability of IAs.

Effects of Low and High Aneurysmal Wall Shear Stress on Endothelial Cell Behavior: Differences and Similarities.

Background: Intracranial aneurysms (IAs) result from abnormal enlargement of the arterial lumen. IAs are mostly quiescent and asymptomatic, but their rupture leads to severe brain damage or death. As the evolution of IAs is hard to predict and intricates medical decision, it is essential to improve our understanding of their pathophysiology. Wall shear stress (WSS) is proposed to influence IA growth and rupture. In this study, we investigated the effects of low and supra-high aneurysmal WSS on endothelial cells (ECs). Methods: Porcine arterial ECs were exposed for 48 h to defined levels of shear stress (2, 30, or 80 dyne/cm2) using an Ibidi flow apparatus. Immunostaining for CD31 or γ-cytoplasmic actin was performed to outline cell borders or to determine cell architecture. Geometry measurements (cell orientation, area, circularity and aspect ratio) were performed on confocal microscopy images. mRNA was extracted for RNAseq analysis. Results: ECs exposed to low or supra-high aneurysmal WSS were more circular and had a lower aspect ratio than cells exposed to physiological flow. Furthermore, they lost the alignment in the direction of flow observed under physiological conditions. The effects of low WSS on differential gene expression were stronger than those of supra-high WSS. Gene set enrichment analysis highlighted that extracellular matrix proteins, cytoskeletal proteins and more particularly the actin protein family were among the protein classes the most affected by shear stress. Interestingly, most genes showed an opposite regulation under both types of aneurysmal WSS. Immunostainings for γ-cytoplasmic actin suggested a different organization of this cytoskeletal protein between ECs exposed to physiological and both types of aneurysmal WSS. Conclusion: Under both aneurysmal low and supra-high WSS the typical arterial EC morphology molds to a more spherical shape. Whereas low WSS down-regulates the expression of cytoskeletal-related proteins and up-regulates extracellular matrix proteins, supra-high WSS induces opposite changes in gene expression of these protein classes. The differential regulation in EC gene expression observed under various WSS translate into a different organization of the ECs' architecture. This adaptation of ECs to different aneurysmal WSS conditions may affect vascular remodeling in IAs.

Robust innate responses to SARS-CoV-2 in children resolve faster than in adults without compromising adaptive immunity.

SARS-CoV-2 infection in children is less severe than it is in adults. We perform a longitudinal analysis of the early innate responses in children and adults with mild infection within household clusters. Children display fewer symptoms than adults do, despite similar initial viral load, and mount a robust anti-viral immune signature typical of the SARS-CoV-2 infection and characterized by early interferon gene responses; increases in cytokines, such as CXCL10 and GM-CSF; and changes in blood cell numbers. When compared with adults, the antiviral response resolves faster (within a week of symptoms), monocytes and dendritic cells are more transiently activated, and genes associated with B cell activation appear earlier in children. Nonetheless, these differences do not have major effects on the quality of SARS-CoV-2-specific antibody responses. Our findings reveal that better early control of inflammation as observed in children may be key for rapidly controlling infection and limiting the disease course.

Longitudinal Analysis of Inflammatory Response to SARS-CoV-2 in the Upper Respiratory Tract Reveals an Association with Viral Load, Independent of Symptoms.

BACKGROUND: SARS-CoV-2 infection leads to high viral loads in the upper respiratory tract that may be determinant in virus dissemination. The extent of intranasal antiviral response in relation to symptoms is unknown. Understanding how local innate responses control virus is key in the development of therapeutic approaches. METHODS: SARS-CoV-2-infected patients were enrolled in an observational study conducted at the Geneva University Hospitals, Switzerland, investigating virological and immunological characteristics. Nasal wash and serum specimens from a subset of patients were collected to measure viral load, IgA specific for the S1 domain of the spike protein, and a cytokine panel at different time points after infection; cytokine levels were analyzed in relation to symptoms. RESULTS: Samples from 13 SARS-CoV-2-infected patients and six controls were analyzed. We found an increase in CXCL10 and IL-6, whose levels remained elevated for up to 3 weeks after symptom onset. SARS-CoV-2 infection also induced CCL2 and GM-CSF, suggesting local recruitment and activation of myeloid cells. Local cytokine levels correlated with viral load but not with serum cytokine levels, nor with specific symptoms, including anosmia. Some patients had S1-specific IgA in the nasal cavity while almost none had IgG. CONCLUSION: The nasal epithelium is an active site of cytokine response against SARS-CoV-2 that can last more than 2 weeks; in this mild COVID-19 cohort, anosmia was not associated with increases in any locally produced cytokines.

Persistence of self-reactive CD8+ T cells in the CNS requires TOX-dependent chromatin remodeling.

Self-reactive CD8+ T cells are important mediators of progressive tissue damage in autoimmune diseases, but the molecular program underlying these cells' functional adaptation is unclear. Here we characterize the transcriptional and epigenetic landscape of self-reactive CD8+ T cells in a mouse model of protracted central nervous system (CNS) autoimmunity and compare it to populations of CNS-resident memory CD8+ T cells emerging from acute viral infection. We find that autoimmune CD8+ T cells persisting at sites of self-antigen exhibit characteristic transcriptional regulation together with distinct epigenetic remodeling. This self-reactive CD8+ T cell fate depends on the transcriptional regulation by the DNA-binding HMG-box protein TOX which remodels more than 400 genomic regions including loci such as Tcf7, which is central to stemness of CD8+ T cells. Continuous exposure to CNS self-antigen sustains TOX levels in self-reactive CD8+ T cells, whereas genetic ablation of TOX in CD8+ T cells results in shortened persistence of self-reactive CD8+ T cells in the inflamed CNS. Our study establishes and characterizes the genetic differentiation program enabling chronic T cell-driven immunopathology in CNS autoimmunity.

Immune response of polarized cystic fibrosis airway epithelial cells infected with Influenza A virus.

BACKGROUND: Cystic fibrosis (CF), a genetic disease caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, is characterized by dysfunction of the immune response in the airway epithelium that leads to prolonged infection, colonization and exacerbated inflammation. In this study, we determined the gene expression profile of airway epithelial cells knockdown for CFTR (CFTR KD) in response to bacterial and viral challenges. METHODS: In a first approach, polarized CFTR KD and their control counterpart (CFTR CTL) cells were stimulated with P. aeruginosa-derived virulence factor flagellin. Next, we developed a model of Influenza A virus (IAV) infection in CTL and CFTR KD polarized cells. mRNA was collected for transcriptome analysis. RESULTS: Beside the expected pro-inflammatory response, Gene Set Enrichment Analysis highlighted key molecular pathways and players involved in IAV and anti-viral interferon signaling. Although IAV replication was similar in both cell types, multiplex gene expression analysis revealed changes of key immune genes dependent on time of infection that were found to be CFTR-dependent and/or IAV-dependent. Interferons are key signaling proteins/cytokines in the antibacterial and antiviral response. To evaluate their impact on the altered gene expression profile in CFTR responses to pathogens, we measured transcriptome changes after exposure to Type I-, Type II- and Type III-interferons. CONCLUSIONS: Our findings reveal target genes in understanding the defective immune response in the CF airway epithelium in the context of viral infection. Information provided in this study would be useful to understand the dysfunctional immune response of the CF airway epithelium during infection.

Daily Viral Kinetics and Innate and Adaptive Immune Response Assessment in COVID-19: a Case Series.

Viral shedding patterns and their correlations with immune responses are still poorly characterized in mild coronavirus (CoV) disease 2019 (COVID-19). We monitored shedding of viral RNA and infectious virus and characterized the immune response kinetics of the first five patients quarantined in Geneva, Switzerland. High viral loads and infectious virus shedding were observed from the respiratory tract despite mild symptoms, with isolation of infectious virus and prolonged positivity by reverse transcriptase PCR (RT-PCR) until days 7 and 19 after symptom onset, respectively. Robust innate responses characterized by increases in activated CD14+ CD16+ monocytes and cytokine responses were observed as early as 2 days after symptom onset. Cellular and humoral severe acute respiratory syndrome (SARS)-CoV-2-specific adaptive responses were detectable in all patients. Infectious virus shedding was limited to the first week after symptom onset. A strong innate response, characterized by mobilization of activated monocytes during the first days of infection and SARS-CoV-2-specific antibodies, was detectable even in patients with mild disease.IMPORTANCE This work is particularly important because it simultaneously assessed the virology, immunology, and clinical presentation of the same subjects, whereas other studies assess these separately. We describe the detailed viral and immune profiles of the first five patients infected by SARS-CoV-2 and quarantined in Geneva, Switzerland. Viral loads peaked at the very beginning of the disease, and infectious virus was shed only during the early acute phase of disease. No infectious virus could be isolated by culture 7 days after onset of symptoms, while viral RNA was still detectable for a prolonged period. Importantly, we saw that all patients, even those with mild symptoms, mount an innate response sufficient for viral control (characterized by early activated cytokines and monocyte responses) and develop specific immunity as well as cellular and humoral SARS-CoV-2-specific adaptive responses, which already begin to decline a few months after the resolution of symptoms.

Interplay of RFX transcription factors 1, 2 and 3 in motile ciliogenesis.

Cilia assembly is under strict transcriptional control during animal development. In vertebrates, a hierarchy of transcription factors (TFs) are involved in controlling the specification, differentiation and function of multiciliated epithelia. RFX TFs play key functions in the control of ciliogenesis in animals. Whereas only one RFX factor regulates ciliogenesis in C. elegans, several distinct RFX factors have been implicated in this process in vertebrates. However, a clear understanding of the specific and redundant functions of different RFX factors in ciliated cells remains lacking. Using RNA-seq and ChIP-seq approaches we identified genes regulated directly and indirectly by RFX1, RFX2 and RFX3 in mouse ependymal cells. We show that these three TFs have both redundant and specific functions in ependymal cells. Whereas RFX1, RFX2 and RFX3 occupy many shared genomic loci, only RFX2 and RFX3 play a prominent and redundant function in the control of motile ciliogenesis in mice. Our results provide a valuable list of candidate ciliary genes. They also reveal stunning differences between compensatory processes operating in vivo and ex vivo.

Vav3 Mediates Pseudomonas aeruginosa Adhesion to the Cystic Fibrosis Airway Epithelium.

Pseudomonas aeruginosa (Pa) represents the leading cause of airway infection in cystic fibrosis (CF). Early airways colonization can be explained by enhanced adhesion of Pa to the respiratory epithelium. RNA sequencing (RNA-seq) on fully differentiated primary cultures of airway epithelial cells from CF and non-CF donors predict that VAV3, ß1 INTEGRIN, and FIBRONECTIN genes are significantly enriched in CF. Indeed, Vav3 is apically overexpressed in CF, associates with active ß1 integrin luminally exposed, and increases fibronectin deposition. These luminal microdomains, rich in fibronectin and ß1 integrin and regulated by Vav3, mediate the increased Pa adhesion to the CF epithelium. Interestingly, Vav3 inhibition normalizes the CF-dependent fibronectin and ß1-integrin ectopic expression, improves the CF epithelial integrity, and prevents the enhanced Pa trapping to the CF epithelium. Through its capacity to promote a luminal complex with active ß1 integrin and fibronectin that favors bacteria trapping, Vav3 may represent a new target in CF.

IL-36 signaling in keratinocytes controls early IL-23 production in psoriasis-like dermatitis.

IL-36R signaling plays an important role in the pathogenesis of psoriasis. We ought to assess the specific function of IL-36R in keratinocytes for the pathology of Aldara-induced psoriasis-like dermatitis. Il36r ΔK mice presenting deletion of IL-36R in keratinocytes were similarly resistant to Aldara-induced ear inflammation as Il36r -/- mice, but acanthosis was only prevented in Il36r -/- mice. FACS analysis revealed that IL-36R signaling in keratinocytes is mandatory for early neutrophil infiltration in Aldara-treated ears. RNASeq and qRT-PCR experiments demonstrated the crucial role of IL-36R signaling in keratinocytes for induction of IL-23, IL-17, and IL-22 at early time points. Taken together, our results demonstrate that IL-36R signaling in keratinocytes plays a major role in the induction of Aldara-induced psoriasis-like dermatitis by triggering early production of IL-23/IL-17/IL-22 cytokines and neutrophil infiltration.

Gestation and lactation exposure to nicotine induces transient postnatal changes in lung alveolar development.

Harmful consequences of cigarette smoke (CS) exposure during lung development can already manifest in infancy. In particular, early life exposure to nicotine, the main component of CS, was shown to affect lung development in animal models. We aimed to characterize the effect of nicotine on alveoli formation. We analyzed the kinetics of normal alveolar development during the alveolarization phase and then looked at the effect of nicotine in a mouse model of gestational and early life exposure. Immunohistochemical staining revealed that the wave of cell proliferation [i.e., vascular endothelial cells, alveolar epithelial cells (AEC) type II and mesenchymal cell] occurs at postnatal day (pnd) 8 in control and nicotine-exposed lungs. However, FACS analysis of individual epithelial alveolar cells revealed nicotine-induced transient increase of AEC type I proliferation and decrease of vascular endothelial cell proliferation at pnd8. Furthermore, nicotine increased the percentage of endothelial cells at pnd2. Transcriptomic data also showed significant changes in nicotine samples compared with the controls on cell cycle-associated genes at pnd2 but not anymore at pnd16. Accordingly, the expression of survivin, involved in cell cycle regulation, also follows a different kinetics in nicotine lung extracts. These changes resulted in an increased lung size detected by stereology at pnd16 but no longer in adult age, suggesting that nicotine can act on the pace of lung maturation. Taken together, our results indicate that early life nicotine exposure could be harmful to alveolar development independently from other toxicants contained in CS.

Human fetal mesoangioblasts reveal tissue-dependent transcriptional signatures.

Mesoangioblasts (MABs) derived from adult skeletal muscles are well-studied adult stem/progenitor cells that already entered clinical trials for muscle regeneration in genetic diseases; however, the transcriptional identity of human fetal MABs (fMABs) remains largely unknown. Herein we analyzed the transcriptome of MABs isolated according to canonical markers from fetal atrium, ventricle, aorta, and skeletal muscles (from 9.5 to 13 weeks of age) to uncover specific gene signatures correlating with their peculiar myogenic differentiation properties inherent to their tissue of origin. RNA-seq analysis revealed for the first time that human MABs from fetal aorta, cardiac (atrial and ventricular), and skeletal muscles display subsets of differentially expressed genes likely representing distinct expression signatures indicative of their original tissue. Identified GO biological processes and KEGG pathways likely account for their distinct differentiation outcomes and provide a set of critical genes possibly predicting future specific differentiation outcomes. This study reveals novel information regarding the potential of human fMABs that may help to improve specific differentiation outcomes relevant for therapeutic muscle regeneration.

Intracellular IL-1 Receptor Antagonist Isoform 1 Released from Keratinocytes upon Cell Death Acts as an Inhibitor for the Alarmin IL-1α.

The inflammatory effects of IL-1α/ß are controlled by IL-1R antagonist (IL-1Ra). One IL-1Ra isoform is secreted, whereas three other isoforms (intracellular IL-1Ra [icIL-1Ra] 1, 2, and 3) are supposed to remain intracellular because of the absence of a signal peptide. In contrast to the well-characterized function of the secreted isoform, the biological role of the intracellular isoforms remains largely unclear. icIL-1Ra1 represents the major isoform in keratinocytes. We created icIL-1Ra1-/- mice and investigated the role of icIL-1Ra1 in Aldara (5% imiquimod)-induced psoriasis-like skin inflammation. Naive icIL-1Ra1-/- mice bred habitually and exhibited a normal phenotype. icIL-1Ra1 deficiency aggravated Aldara-induced skin inflammation, as demonstrated by increased ear thickness and increased mRNA levels of key proinflammatory cytokines. No intracellular effect of icIL-1Ra1 could be detected in isolated keratinocytes using RNA-sequencing analysis; however, Aldara treatment led to caspase 1/11-, caspase 8-, and RIPK3-independent keratinocyte cell death accompanied by the release of both icIL-1Ra1 and IL-1α. Furthermore, blocking IL-1α attenuated the clinical severity of Aldara-induced ear thickening in icIL-1Ra1-/- mice. Our data suggest that upon keratinocyte damage icIL-1Ra1 acts extracellularly as an antagonist of the alarmin IL-1α to immediately counteract its inflammatory effects.