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Background: There is a need for early therapeutic interventions after traumatic brain injury (TBI) to prevent neurodegeneration. Microglia/macrophage (M/M) depletion and repopulation after treatment with colony stimulating factor 1 receptor (CSF1R) inhibitors reduces neurodegeneration. The present study investigates short- and long-term consequences after CSF1R inhibition during the early phase after TBI.
Methods: Sex-matched mice were subjected to TBI and CSF1R inhibition by PLX3397 for 5 days and sacrificed at 5 or 30 days post injury (dpi). Neurological deficits were monitored and brain tissues were examined for histo- and molecular pathological markers. RNAseq was performed with 30 dpi TBI samples.
Results: At 5 dpi, CSF1R inhibition attenuated the TBI-induced perilesional M/M increase and associated gene expressions by up to 50%. M/M attenuation did not affect structural brain damage at this time-point, impaired hematoma clearance, and had no effect on IL-1β expression. At 30 dpi, following drug discontinuation at 5 dpi and M/M repopulation, CSF1R inhibition attenuated brain tissue loss regardless of sex, as well as hippocampal atrophy and thalamic neuronal loss in male mice. Selected gene markers of brain inflammation and apoptosis were reduced in males but increased in females after early CSF1R inhibition as compared to corresponding TBI vehicle groups. Neurological outcome in behaving mice was almost not affected. RNAseq and gene set enrichment analysis (GSEA) of injured brains at 30 dpi revealed more genes associated with dendritic spines and synapse function after early CSF1R inhibition as compared to vehicle, suggesting improved neuronal maintenance and recovery. In TBI vehicle mice, GSEA showed high oxidative phosphorylation, oxidoreductase activity and ribosomal biogenesis suggesting oxidative stress and increased abundance of metabolically highly active cells. More genes associated with immune processes and phagocytosis in PLX3397 treated females vs males, suggesting sex-specific differences in response to early CSF1R inhibition after TBI.
Conclusions: M/M attenuation after CSF1R inhibition via PLX3397 during the early phase of TBI reduces long-term brain tissue loss, improves neuronal maintenance and fosters synapse recovery. Overall effects were not sex-specific but there is evidence that male mice benefit more than female mice.
Die Entzündung ist eine Folge von Reaktionen mit der Zielsetzung, die Ausbreitung einer Gewebeschädigung, oder eines Infektionserregers einzudämmen. Zelluläre und humorale Mechanismen interagieren dabei in einem komplexen Netzwerk. In diesem Übersichtsbeitrag zeigen wir die wichtigsten Wege des inflammatorischen Reaktionsgeschehens auf und diskutieren die Bedeutung von Laboratoriumsuntersuchungen für die Diagnostik und das Monitoring von Entzündungen.
Wesentliche Schritte im Ablauf der Entzündungsreaktion sind
- die Synthese von Prostaglandinen aus Arachidonsäure, die durch Phospholipasen A2 (PLA2)-katalysierte Hydrolyse aus Membranphospholipiden gebildet wird;
- Interaktionen zwischen Gefäßendothel und Leukozyten, die Leukozytenextravasation und die Freisetzung freier Sauerstoffradikale und von Elastase im Gewebe;
- die Bildung inflammatorischer Cytokine, ihr Effekt auf Entzündungszellen und ihre systemische Wirkung auf Organe;
- die Synthese von Akute-Phase-Proteinen, deren Plasmakonzentration bei Entzündung als Antwort auf eine Vielfalt von Schädigungen ansteigt.
Zur Diagnostik und Verlaufsbeurteilung entzündlicher Krankheiten hat die Bestimmung des C-reaktiven Proteins den höchsten Stellenwert. Die Elastase hat nur eine begrenzte Bedeutung. Die Bestimmung von PLA2, der 'inflammatorischen Cytokine TNFa, IL-1, IL-6 und des s!L-2R als generelle Entzündungsmarker kann in der Routinediagnostik noch nicht empfohlen werden. Eingehende klinische Untersuchungen zur diagnostischen Bedeutung müssen noch abgewartet werden.
Highlights
• Suicides which occurred in a biologics trial targeting the IL-17R are revisited.
• High IL-17 levels are found in depression by the majority of reports.
• Results from studies regarding IL-17 and psychosis are mixed.
• Very few psychiatric studies investigated IL-17 signalling in suicidality.
• Potential mechanisms how IL-17 influences neuro-inflammation are described.
Abstract:
Interleukin 17 (IL-17) is a potent pro-inflammatory cytokine which plays a role in autoimmune disorders, such as psoriasis and multiple sclerosis, and is important for the defense against pathogens, particularly in the gut. However, IL-17 has recently also gained attention in association with suicidal behavior. In this review, we review the literature regarding IL-17 in psychiatric disorders and suicidality. We also take a closer look at the suicides which occurred in the clinical trial for psoriasis with brodalumab, a monoclonal antibody targeting the IL-17 receptor. Lastly, we discuss potential working mechanisms relevant to neuroinflammation and the possible involvement of IL-17.
IL-22 is an immunoregulatory cytokine displaying pathological functions in models of autoimmunity like experimental psoriasis. Understanding molecular mechanisms driving IL-22, together with knowledge on the capacity of current immunosuppressive drugs to target this process, may open an avenue to novel therapeutic options. Here, we sought to characterize regulation of human IL22 gene expression with focus on the established model of Jurkat T cells. Moreover, effects of the prototypic immunosuppressant cyclosporin A (CsA) were investigated. We report that IL-22 induction by TPA/A23187 (T/A) or αCD3 is inhibited by CsA or related FK506. Similar data were obtained with peripheral blood mononuclear cells or purified CD3(+) T cells. IL22 promoter analysis (-1074 to +156 bp) revealed a role of an NF-AT (-95/-91 nt) and a CREB (-194/-190 nt) binding site for gene induction. Indeed, binding of CREB and NF-ATc2, but not c-Rel, under the influence of T/A to those elements could be proven by ChIP. Because CsA has the capability to impair IκB kinase (IKK) complex activation, the IKKα/β inhibitor IKKVII was evaluated. IKKVII likewise reduced IL-22 induction in Jurkat cells and peripheral blood mononuclear cells. Interestingly, transfection of Jurkat cells with siRNA directed against IKKα impaired IL22 gene expression. Data presented suggest that NF-AT, CREB, and IKKα contribute to rapid IL22 gene induction. In particular the crucial role of NF-AT detected herein may form the basis of direct action of CsA on IL-22 expression by T cells, which may contribute to therapeutic efficacy of the drug in autoimmunity.
Endocannabinoids are important lipid-signaling mediators. Both protective and deleterious effects of endocannabinoids in the cardiovascular system have been reported but the mechanistic basis for these contradicting observations is unclear. We set out to identify anti-inflammatory mechanisms of endocannabinoids in the murine aorta and in human vascular smooth muscle cells (hVSMC). In response to combined stimulation with cytokines, IL-1β and TNFα, the murine aorta released several endocannabinoids, with anandamide (AEA) levels being the most significantly increased. AEA pretreatment had profound effects on cytokine-induced gene expression in hVSMC and murine aorta. As revealed by RNA-Seq analysis, the induction of a subset of 21 inflammatory target genes, including the important cytokine CCL2 was blocked by AEA. This effect was not mediated through AEA-dependent interference of the AP-1 or NF-κB pathways but rather through an epigenetic mechanism. In the presence of AEA, ATAC-Seq analysis and chromatin-immunoprecipitations revealed that CCL2 induction was blocked due to increased levels of H3K27me3 and a decrease of H3K27ac leading to compacted chromatin structure in the CCL2 promoter. These effects were mediated by recruitment of HDAC4 and the nuclear corepressor NCoR1 to the CCL2 promoter. This study therefore establishes a novel anti-inflammatory mechanism for the endogenous endocannabinoid AEA in vascular smooth muscle cells. Furthermore, this work provides a link between endogenous endocannabinoid signaling and epigenetic regulation.
Die Herzinsuffizienz im hohen Lebensalter spielt wegen der demografischen Entwicklung in Deutschland eine zunehmende Rolle im perioperativen Setting der Herzchirurgie. Auch nehmen strukturelle Schäden und Dysfunktionen am Herzen aufgrund von chronischen kardiovaskulären Erkrankungen zu. Diese bedürfen oftmals einer operativen Intervention als Therapie. Zum perioperativen Monitoring werden verschiedene Laborwerte herangezogen, um mögliche Komplikationen frühzeitig zu erkennen. In der vorliegenden Studie wurde das Augenmerk auf Hochrisikopatienten mit Herzinsuffizienz gelegt. Die Fragestellung behandelt, ob sich gewisse Entzündungsmarker bei Hochrisikopatienten, vor allem im hohen Lebensalter, bei verschiedenen Risikogruppen unterscheiden. Es handelt sich um eine prospektive Beobachtungsstudie, in der 94 Patienten perioperativ untersucht wurden. Diese wurden in zwei Gruppen mit jeweils 47 Patienten unterteilt. Die eine enthielt Patienten unter 75 Jahren mit einer linksventrikulären Ejektionsfraktion <35%, einer operationsbedürftigen Mehrklappen-Erkrankung oder einer Herzklappendysfunktion, kombiniert mit einer operationswürdigen koronaren Herzkrankheit. In der zweiten Gruppe wählte man Patienten in einem Alter ab 75 Jahren mit einer operationsbedürftigen Herzkrankheit. Bestimmt wurden die Entzündungsparameter CRP, Procalcitonin, Interleukin 6 und Interleukin 8. Zusätzlich wurde NT-pro-BNP als Marker für Herzinsuffizienz bestimmt. Die Blutentnahmen erfolgten präoperativ, unmittelbar postoperativ, am 1.,2. und 5. Tag postoperativ. Die präoperativen Werte wurden mit dem Risikoprofil der Patienten in Korrelation gesetzt. Dabei stach heraus, dass bei Patienten mit stattgehabter kardialer Dekompensation die Werte von CRP, NT-proBNP, IL6 und IL8 signifikant erhöht waren. Postoperativ erlitten diese Patienten häufiger eine Rethorakotomie. Außerdem ergab sich ein signifikanter Zusammenhang zwischen der Höhe der postoperativen Entzündungsparameter und dem Auftreten einer postoperativen Sepsis oder Infektion. Hier zeigte sich, dass CRP erst ab dem 5. Tag postoperativ als Indikator für eine solche gewertet werden kann, während Procalcitonin, IL6 und IL8 schon unmittelbar postoperativ als Parameter für das Auftreten einer Sepsis oder Infektion herangezogen werden können. In der vorliegenden Studie wurden jedoch nicht die Zeitpunkte der postoperativen Komplikationen bestimmt, was eine Prüfung auf Unterschied mit den postoperativen Etnzündungswerten erschwert. Zwischen den perioperativen Verläufen der bestimmten Parameter gab es zwischen den beiden Gruppen keinen signifikanten Unterschied. Dies impliziert, dass eine Ejektionsfraktion <35%/eine Mehrklappen-Erkrankung und ein Alter über 75 Jahren bei gröstenteils normwertiger EF als ebenbürtige Risikofaktoren angesehen werden können.
Highligths
• Immune-inflammatory alterations might appear in subjects with ADHD.
• Blood levels of tumor necrosis factor-α might be reduced in individuals with ADHD.
• Individuals with ADHD might show elevated blood levels of interleukin-6.
Abstract
It has been observed that subclinical inflammation might be involved in the pathophysiology of attention deficit/hyperactivity disorder (ADHD). However, studies investigating peripheral blood levels of immune-inflammatory markers have provided mixed findings. We performed a systematic review and meta-analysis of studies comparing unstimulated serum or plasma levels of C-reactive protein (CRP) and cytokines in subjects with ADHD and healthy controls (the PROSPERO registration number: CRD 42021276869). Online searches covered the publication period until 30th Sep 2021 and random-effects meta-analyses were carried out. Out of 1844 publication records identified, 10 studies were included. The levels of interleukin (IL)-6 were significantly higher in studies of participants up to the age of 18 years (k = 10, g = 0.70, 95%CI: 0.10–1.30, p = 0.023) and after including those above the age of 18 years (k = 10, g = 0.71, 95%CI: 0.12–1.31, p = 0.019). In turn, the levels of tumor necrosis factor-α (TNF-α) were significantly lower in subjects with ADHD compared to healthy controls (k = 7, g = −0.16, 95%CI: −0.30 - -0.03, p = 0.020). Individual studies had a high contribution to the overall effect, since the overall effect was no longer significant after removing single studies. No significant differences were found with respect to the levels of CRP, IL-1β, IL-10 and interferon-γ. The present findings indicate that individuals with ADHD tend to show elevated levels of IL-6 and reduced levels of TNF-α. Larger and longitudinal studies recording potential confounding factors and comorbid psychopathology are needed to confirm our findings.
Peroxisome proliferator-activated receptor γ (PPARγ) gained considerable interest as a therapeutic target during chronic inflammatory diseases. Remarkably, the pathogenesis of diseases such as multiple sclerosis or Alzheimer is associated with impaired PPARγ expression. Considering that regulation of PPARγ expression during inflammation is largely unknown, we were interested in elucidating underlying mechanisms. To this end, we initiated an inflammatory response by exposing primary human macrophages to lipopolysaccharide (LPS) and observed a rapid decline of PPARγ1 expression. Because promoter activities were not affected by LPS, we focused on mRNA stability and noticed a decreased mRNA half-life. As RNA stability is often regulated via 3′-untranslated regions (UTRs), we analyzed the impact of the PPARγ-3′-UTR by reporter assays using specific constructs. LPS significantly reduced luciferase activity of the pGL3-PPARγ-3′-UTR, suggesting that PPARγ1 mRNA is destabilized. Deletion or mutation of a potential microRNA-27a/b (miR-27a/b) binding site within the 3′-UTR restored luciferase activity. Moreover, inhibition of miR-27b, which was induced upon LPS exposure, partially reversed PPARγ1 mRNA decay, whereas miR-27b overexpression decreased PPARγ1 mRNA content. In addition, LPS further reduced this decay. The functional relevance of miR-27b-dependent PPARγ1 decrease was proven by inhibition or overexpression of miR-27b, which affected LPS-induced expression of the pro-inflammatory cytokines tumor necrosis factor α (TNFα) and interleukin (IL)-6. We provide evidence that LPS-induced miR-27b contributes to destabilization of PPARγ1 mRNA. Understanding molecular mechanisms decreasing PPARγ might help to better appreciate inflammatory diseases.
Aims: Long non-coding RNAs (lncRNAs) have been shown to regulate numerous processes in the human genome, but the function of these transcripts in vascular aging is largely unknown. We aim to characterize the expression of lncRNAs in endothelial aging and analyse the function of the highly conserved lncRNA H19.
Methods and results: H19 was downregulated in endothelium of aged mice. In human, atherosclerotic plaques H19 was mainly expressed by endothelial cells and H19 was significantly reduced in comparison to healthy carotid artery biopsies. Loss of H19 led to an upregulation of p16 and p21, reduced proliferation and increased senescence in vitro. Depletion of H19 in aortic rings of young mice inhibited sprouting capacity. We generated endothelial-specific inducible H19 deficient mice (H19iEC-KO), resulting in increased systolic blood pressure compared with control littermates (Ctrl). These H19iEC-KO and Ctrl mice were subjected to hindlimb ischaemia, which showed reduced capillary density in H19iEC-KO mice. Mechanistically, exon array analysis revealed an involvement of H19 in IL-6 signalling. Accordingly, intercellular adhesion molecule 1 and vascular cell adhesion molecule 1 were upregulated upon H19 depletion. A luciferase reporter screen for differential transcription factor activity revealed STAT3 as being induced upon H19 depletion and repressed after H19 overexpression. Furthermore, depletion of H19 increased the phosphorylation of STAT3 at TYR705 and pharmacological inhibition of STAT3 activation abolished the effects of H19 silencing on p21 and vascular cell adhesion molecule 1 expression as well as proliferation.
Conclusion: These data reveal a pivotal role for the lncRNA H19 in controlling endothelial cell aging.
Aims: Systemic inflammatory response, identified by increased total leucocyte counts, was shown to be a strong predictor of mortality after transcatheter aortic valve implantation (TAVI). Yet the mechanisms of inflammation-associated poor outcome after TAVI are unclear. Therefore, the present study aimed at investigating individual inflammatory signatures and functional heterogeneity of circulating myeloid and T-lymphocyte subsets and their impact on 1 year survival in a single-centre cohort of patients with severe aortic stenosis undergoing TAVI. Methods and results: One hundred twenty-nine consecutive patients with severe symptomatic aortic stenosis admitted for transfemoral TAVI were included. Blood samples were obtained at baseline, immediately after, and 24 h and 3 days after TAVI, and these were analysed for inflammatory and cardiac biomarkers. Myeloid and T-lymphocyte subsets were measured using flow cytometry. The inflammatory parameters were first analysed as continuous variables; and in case of association with outcome and area under receiver operating characteristic (ROC) curve (AUC) ≥ 0.6, the values were dichotomized using optimal cut-off points. Several baseline inflammatory parameters, including high-sensitivity C-reactive protein (hsCRP; HR = 1.37, 95% CI: 1.15–1.63; P < 0.0001) and IL-6 (HR = 1.02, 95% CI: 1.01–1.03; P = 0.003), lower counts of Th2 (HR = 0.95, 95% CI: 0.91–0.99; P = 0.009), and increased percentages of Th17 cells (HR = 1.19, 95% CI: 1.02–1.38; P = 0.024) were associated with 12 month all-cause mortality. Among postprocedural parameters, only increased post-TAVI counts of non-classical monocytes immediately after TAVI were predictive of outcome (HR = 1.03, 95% CI: 1.01–1.05; P = 0.003). The occurrence of SIRS criteria within 48 h post-TAVI showed no significant association with 12 month mortality (HR = 0.57, 95% CI: 0.13–2.43, P = 0.45). In multivariate analysis of discrete or dichotomized clinical and inflammatory variables, the presence of diabetes mellitus (HR = 3.50; 95% CI: 1.42–8.62; P = 0.006), low left ventricular (LV) ejection fraction (HR = 3.16; 95% CI: 1.35–7.39; P = 0.008), increased baseline hsCRP (HR = 5.22; 95% CI: 2.09–13.01; P < 0.0001), and low baseline Th2 cell counts (HR = 8.83; 95% CI: 3.02–25.80) were significant predictors of death. The prognostic value of the linear prediction score calculated of these parameters was superior to the Society of Thoracic Surgeons score (AUC: 0.88; 95% CI: 0.78–0.99 vs. 0.75; 95% CI: 0.64–0.86, respectively; P = 0.036). Finally, when analysing LV remodelling outcomes, ROC curve analysis revealed that low numbers of Tregs (P = 0.017; AUC: 0.69) and increased Th17/Treg ratio (P = 0.012; AUC: 0.70) were predictive of adverse remodelling after TAVI. Conclusions: Our findings demonstrate an association of specific pre-existing inflammatory phenotypes with increased mortality and adverse LV remodelling after TAVI. Distinct monocyte and T-cell signatures might provide additive biomarkers to improve pre-procedural risk stratification in patients referred to TAVI for severe aortic stenosis.