Rehman, R;Miller, M;Krishnamurthy, SS;Kjell, J;Elsayed, L;Hauck, SM;Olde Heuvel, F;Conquest, A;Chandrasekar, A;Ludolph, A;Boeckers, T;Mulaw, MA;Goetz, M;Morganti-Kossmann, MC;Takeoka, A;Roselli, F;
PMID: 36577378 | DOI: 10.1016/j.celrep.2022.111867
The complexity of signaling events and cellular responses unfolding in neuronal, glial, and immune cells upon traumatic brain injury (TBI) constitutes an obstacle in elucidating pathophysiological links and targets for intervention. We use array phosphoproteomics in a murine mild blunt TBI to reconstruct the temporal dynamics of tyrosine-kinase signaling in TBI and then scrutinize the large-scale effects of perturbation of Met/HGFR, VEGFR1, and Btk signaling by small molecules. We show Met/HGFR as a selective modifier of early microglial response and that Met/HGFR blockade prevents the induction of microglial inflammatory mediators, of reactive microglia morphology, and TBI-associated responses in neurons and vasculature. Both acute and prolonged Met/HGFR inhibition ameliorate neuronal survival and motor recovery. Early elevation of HGF itself in the cerebrospinal fluid of TBI patients suggests that this mechanism has translational value in human subjects. Our findings identify Met/HGFR as a modulator of early neuroinflammation in TBI with promising translational potential.
Choi, BR;Johnson, KR;Maric, D;McGavern, DB;
PMID: 37248420 | DOI: 10.1038/s41590-023-01521-1
Cerebrovascular injury (CVI) is a common pathology caused by infections, injury, stroke, neurodegeneration and autoimmune disease. Rapid resolution of a CVI requires a coordinated innate immune response. In the present study, we sought mechanistic insights into how central nervous system-infiltrating monocytes program resident microglia to mediate angiogenesis and cerebrovascular repair after an intracerebral hemorrhage. In the penumbrae of human stroke brain lesions, we identified a subpopulation of microglia that express vascular endothelial growth factor A. These cells, termed 'repair-associated microglia' (RAMs), were also observed in a rodent model of CVI and coexpressed interleukin (IL)-6Ra. Cerebrovascular repair did not occur in IL-6 knockouts or in mice lacking microglial IL-6Ra expression and single-cell transcriptomic analyses revealed faulty RAM programming in the absence of IL-6 signaling. Infiltrating CCR2+ monocytes were the primary source of IL-6 after a CVI and were required to endow microglia with proliferative and proangiogenic properties. Faulty RAM programming in the absence of IL-6 or inflammatory monocytes resulted in poor cerebrovascular repair, neuronal destruction and sustained neurological deficits that were all restored via exogenous IL-6 administration. These data provide a molecular and cellular basis for how monocytes instruct microglia to repair damaged brain vasculature and promote functional recovery after injury.
Arthritis Rheumatol. 2015 Apr 27.
Makki MS, Haseeb A, Haqqi TM.
PMID: 25917063 | DOI: 10.1002/art.39173
Abstract OBJECTIVE: Enhanced IL-6 expression plays an important role in the pathogenesis of osteoarthritis (OA). MCPIP1 is a novel post-transcriptional regulator of IL-6 expression and is targeted by miR-9. We investigated the MCPIP1 expression in OA cartilage and explored whether targeting of MCPIP1 by miR-9 contributes to enhanced IL-6 expression in OA. METHODS: Gene and protein expression in IL-1β-stimulated human OA chondrocytes/cartilage was determined by TaqMan assays and immunoblotting respectively. MCPIP1 and IL-6 mRNA expression at single cell level was analyzed using RNAScopeTM . MCPIP1 protein interaction with IL-6 mRNA was investigated using RNA immunoprecipitation (RIP). Transient transfections were used for siRNA mediated knockdown and overexpression of MCPIP1, its RNAse defective mutant, miR-9 or antagomir. Role of signaling pathways was evaluated using small molecule inhibitors. Binding of miR-9 with the "seed sequence" in the 3'UTR of MCPIP1 mRNA was investigated using a luciferase reporter assay. RESULTS: MCPIP1 mRNA expression was low but expression of miR-9 and IL-6 was high in the damaged OA cartilage. In IL-1β-stimulated OA chondrocytes expression of miR-9 and MCPIP1 was mutually exclusive and increase in miR-9 expression level correlated with reduced MCPIP1 expression and enhanced IL-6 expression. MCPIP1 protein directly binds with IL-6 mRNA and over-expression of wild type MCPIP1 destabilized the IL-6 mRNA. MCPIP1 expression was altered by overexpression or inhibition of miR-9. Transfection with miR-9 mimics inhibited the reporter activity and mutation of the "seed sequence" abolished the repression of reporter activity. CONCLUSIONS: These studies implicate miR-9-mediated suppression of MCPIP1 in OA pathogenesis via upregulation of IL-6 expression in IL-1β-stimulated human OA chondrocytes. This article is protected by copyright. All rights reserved.
Cancer Prev Res (Phila). 2015 May 19.
Dietary carcinogens, such as 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), and chronic inflammation have each been implicated as etiological agents in prostate cancer. We hypothesized that bacterial prostatitis would accelerate PhIP-induced pre-invasive lesions in the rat prostate. Male Fischer 344 rats were assigned into 4 groups: Control (untreated), PhIP (200 ppm in the diet for 20 weeks), E. coli (prostatic inoculation in week 10), or PhIP+E. coli. Study animals were monitored for a total of 52 weeks and were euthanized as necessary based on strict criteria for health status and tumor burden. Animals treated with E. coli initially developed acute and chronic inflammation in all lobes of the prostate, whereas inflammation was observed predominantly in the ventral lobe at time of death. PhIP+E. coli-treated animals exhibited a marked decrease in survival compared to PhIP-alone treated animals as a result of an increase in the number of invasive cancers that developed at multiple sites including the skin, small intestine, and Zymbal's gland. Despite their earlier mortality, PhIP+E. coli-treated animals developed an increased average number of precancerous lesions within the prostate compared to PhIP-treated animals, with a significantly increased Ki-67 index. Multiplexed serum cytokine analysis indicated an increase in the level of circulating IL-6 and IL-12 in PhIP+E. coli-treated animals. Elevated serum IL-6 levels correlated with the development of precancerous lesions within the prostate. These results suggest that bacterial infections and dietary carcinogens - two conceivably preventable cancer risk factors - may synergistically promote tumorigenesis.
Short KR, Veeris R, Leijten LM, van den Brand JM, Jong VL, Stittelaar K, Osterhaus ADME, Andeweg A, van Riel D.
Short KR, Veeris R, Leijten LM, van den Brand JM, Jong VL, Stittelaar K, Osterhaus ADME, Andeweg A, van Riel D.
PMID: - | DOI: 10.1093/infdis/jix281
Severe influenza is often associated with disease manifestations outside the respiratory tract. Whilst pro-inflammatory cytokines can be detected in the lungs and blood of infected patients, the role of extra-respiratory organs in the production of pro-inflammatory cytokines is unknown. Here, we show that both pandemic H1N1 and highly pathogenic H5N1 virus induce expression of TNFα, IL-6 and IL-8 in the respiratory tract and central nervous system. In addition, H5N1 virus induced cytokines in the heart, pancreas, spleen, liver and jejunum. Together, these data suggest that extra-respiratory tissues contribute to systemic cytokine responses which may increase the severity of influenza.
Periyasamy P, Thangaraj A, Guo ML, Hu G, Callen S, Buch S.
PMID: 29760177 | DOI: 10.1523/JNEUROSCI.3474-17.2018
The present study demonstrates HIV-1 Tat-mediated epigenetic downregulation of microglial miR-124 and its association with microglial activation. Exposure of mouse primary microglia isolated from newborn pups of either sex to HIV-1 Tat resulted in decreased expression of primary miR-124-1, primary miR-124-2 as well as the mature miR-124. In parallel, HIV-1 Tat exposure to mouse primary microglial cellsresulted in increased expression of DNA methylation enzymes, such as DNMT1, DNMT3A, and DNMT3B that were also accompanied by increased global DNA methylation. Bisulfite-converted genomic DNA sequencing in the HIV-1 Tat exposed mouse primary microglial cellsfurther confirmed increased DNA methylation of the primary miR-124-1 and primary miR-124-2 promoters. Bioinformatic analyses identified MECP2 as a novel 3'-UTR target of miR-124. This was further validated in mouse primary microglial cells wherein HIV-1 Tat-mediated downregulation of miR-124 resulted in increased expression of MECP2, leading in turn to further repression of miR-124 via the feedback loop. In addition to MECP2, miR-124 also modulated the levels of STAT3 through its binding to the 3'-UTR, leading to microglial activation. Luciferase assays and Ago2 immunoprecipitation determined the direct binding between miR-124 and 3'-UTR of both MECP2 and STAT3. Gene silencing of MECP2 and DNMT1 and overexpression of miR-124 blocked HIV-1 Tat-mediated downregulation of miR-124 and microglial activation. In vitro findings were also confirmed in the basal ganglia of SIV-infected rhesus macaques (both sexes). In summary, our findings demonstrate a novel mechanism of HIV-1 Tat-mediated activation of microglia via downregulation of miR-124, leading ultimately to increased MECP2 and STAT3 signaling.
SIGNIFICANCE STATEMENT
Despite the effectiveness of combination antiretroviral therapy in controlling viremia, the CNS continues to harbor viral reservoirs. The persistence of low-level virus replication leads to the accumulation of early viral proteins including HIV-1 Tat protein. Understanding the epigenetic/molecular mechanism(s) by which viral proteins such as HIV-1 Tat can activate microglia is thus of paramount importance. This study demonstrated HIV-1 Tat-mediated DNA methylation of the miR-124 promoter leads to its downregulation with a concomitant upregulation of the MECP2-STAT3-IL6 resulting in microglial activation. These findings reveal an unexplored epigenetic/molecular mechanism(s) underlying HIV-1 Tat-mediated microglial activation, thereby providing a potential target for the development of therapeutics aimed at ameliorating microglial activation and neuroinflammation in the context of HIV-1 infection.
Becker, K;Weigelt, CM;Fuchs, H;Viollet, C;Rust, W;Wyatt, H;Huber, J;Lamla, T;Fernandez-Albert, F;Simon, E;Zippel, N;Bakker, RA;Klein, H;Redemann, NH;
PMID: 36371417 | DOI: 10.1038/s41598-022-23065-4
Retinopathies are multifactorial diseases with complex pathologies that eventually lead to vision loss. Animal models facilitate the understanding of the pathophysiology and identification of novel treatment options. However, each animal model reflects only specific disease aspects and understanding of the specific molecular changes in most disease models is limited. Here, we conducted transcriptome analysis of murine ocular tissue transduced with recombinant Adeno-associated viruses (AAVs) expressing either human VEGF-A, TNF-α, or IL-6. VEGF expression led to a distinct regulation of extracellular matrix (ECM)-associated genes. In contrast, both TNF-α and IL-6 led to more comparable gene expression changes in interleukin signaling, and the complement cascade, with TNF-α-induced changes being more pronounced. Furthermore, integration of single cell RNA-Sequencing data suggested an increase of endothelial cell-specific marker genes by VEGF, while TNF-α expression increased the expression T-cell markers. Both TNF-α and IL-6 expression led to an increase in macrophage markers. Finally, transcriptomic changes in AAV-VEGF treated mice largely overlapped with gene expression changes observed in the oxygen-induced retinopathy model, especially regarding ECM components and endothelial cell-specific gene expression. Altogether, our study represents a valuable investigation of gene expression changes induced by VEGF, TNF-α, and IL-6 and will aid researchers in selecting appropriate animal models for retinopathies based on their agreement with the human pathophysiology.
Chen, K;Wang, P;Chen, J;Ying, Y;Chen, Y;Gilson, E;Lu, Y;Ye, J;
PMID: 35203601 | DOI: 10.3390/biomedicines10020392
Ataxia-telangiectasia mutated (ATM) is a key DNA damage signaling kinase that is mutated in humans with ataxia-telangiectasia (A-T) syndrome. This syndrome is characterized by neurodegeneration, immune abnormality, cancer predisposition, and premature aging. To better understand the function of ATM in vivo, we engineered a viable zebrafish model with a mutated atm gene. Zebrafish atm loss-of-function mutants show characteristic features of A-T-like motor disturbance, including coordination disorders, immunodeficiency, and tumorigenesis. The immunological disorder of atm homozygote fish is linked to the developmental blockade of hematopoiesis, which occurs at the adulthood stage and results in a decrease in infection defense but, with little effect on wound healing. Malignant neoplasms found in atm mutant fish were mainly nerve sheath tumors and myeloid leukemia, which rarely occur in A-T patients or Atm-/- mice. These results underscore the importance of atm during immune cell development. This zebrafish A-T model opens up a pathway to an improved understanding of the molecular basis of tumorigenesis in A-T and the cellular role of atm.
Xing, J;Chen, K;Gao, S;Pousse, M;Ying, Y;Wang, B;Chen, L;Wang, C;Wang, L;Hu, W;Lu, Y;Gilson, E;Ye, J;
PMID: 36644807 | DOI: 10.1111/acel.13780
The contribution of cellular senescence to the behavioral changes observed in the elderly remains elusive. Here, we observed that aging is associated with a decline in protein phosphatase 2A (PP2A) activity in the brains of zebrafish and mice. Moreover, drugs activating PP2A reversed age-related behavioral changes. We developed a transgenic zebrafish model to decrease PP2A activity in the brain through knockout of the ppp2r2c gene encoding a regulatory subunit of PP2A. Mutant fish exhibited the behavioral phenotype observed in old animals and premature accumulation of neural cells positive for markers of cellular senescence, including senescence-associated β-galactosidase, elevated levels cdkn2a/b, cdkn1a, senescence-associated secretory phenotype gene expression, and an increased level of DNA damage signaling. The behavioral and cell senescence phenotypes were reversed in mutant fish through treatment with the senolytic ABT263 or diverse PP2A activators as well as through cdkn1a or tp53 gene ablation. Senomorphic function of PP2A activators was demonstrated in mouse primary neural cells with downregulated Ppp2r2c. We conclude that PP2A reduction leads to neural cell senescence thereby contributing to age-related behavioral changes and that PP2A activators have senotherapeutic properties against deleterious behavioral effects of brain aging.
NK-B cell cross talk induces CXCR5 expression on natural killer cells
Rascle, P;Jacquelin, B;Petitdemange, C;Contreras, V;Planchais, C;Lazzerini, M;Dereuddre-Bosquet, N;Le Grand, R;Mouquet, H;Huot, N;Müller-Trutwin, M;
| DOI: 10.1016/j.isci.2021.103109
B cell follicles (BCFs) in lymph nodes (LNs) are generally exempt of CD8+ T and NK cells. African green monkeys (AGMs), a natural host of simian immunodeficiency virus (SIV), display NK cell-mediated viral control in BCF. NK cell migration into BCF in chronically SIVagm-infected AGM is associated with CXCR5+ NK cells. We aimed to identify the mechanism leading to CXCR5 expression on NK cells. We show that CXCR5+ NK cells in LN were induced following SIVagm infection. CXCR5+ NK cells accumulated preferentially in BCF with proliferating B cells. Autologous NK-B cell co-cultures in transwell chambers induced CXCR5+ NK cells. Transcriptome analysis of CXCR5+ NK cells revealed expression of bcl6 and IL6R. IL-6 induced CXCR5 on AGM and human NK cells. IL6 mRNA was detected in LN at higher levels during SIVagm than SIVmac infection and often produced by plasma cells. Our study reveals a mechanism of B cell-dependent NK cell regulation.
Kraft L, Erdenesukh T, Sauter M, Tschöpe C, Klingel K.
PMID: 30673858 | DOI: 10.1007/s00395-019-0719-0
Coxsackieviruses of group B (CVB) are well-known causes of acute and chronic myocarditis. Chronic myocarditis can evolve into dilated cardiomyopathy (DCM) characterized by fibrosis and cardiac remodeling. Interleukin-1β (IL-1β) plays a decisive role in the induction of the inflammatory response as a consequence of viral replication. In this study, we analyzed the effects of IL-1β neutralization on the transition of acute to chronic myocarditis in a mouse model of CVB3 myocarditis. Mice were treated with an anti-murine IL-1β antibody as a surrogate for Canakinumab at different time points post CVB3 infection. Treatment was performed in the early phase (day 1-14 pi, day 3-14 pi) or at a later stage of myocarditis (day 14-28 pi). Subsequently, the hearts were examined histologically, immunohistochemically and by molecular biology. A significant reduction of viral replication, cardiac damage and inflammation was found after administration of the antibody in the early phase and in the later phase of infection. Furthermore, less collagen I deposition and a considerable reduction of fibrosis were found in antibody-treated mice. Using microarray analysis, a significant upregulation of various extracellular matrix and fibrosis-associated molecules was found in CVB3-infected mice, including TGF-β, TIMP-1 and MMP12, as well as diverse matricellular proteins, whereas, these molecules were significantly downregulated in all IL-1β antibody-treated infected mice. Neutralization of IL-1β at different stages of enteroviral infection prevents the development of chronic viral myocarditis by reducing inflammation, interstitial fibrosis and adverse cardiac remodeling. These findings are relevant for the treatment of patients with acute and chronic myocarditis.
Interleukin-6 In Anca-Associated Vasculitis: Rationale For Successful Treatment with Tocilizumab
Seminars in Arthritis and Rheumatism.
Berti A, Cavalli G, Campochiaro C, Guglielmi B, Baldissera E, Cappio S, Sabbadini MG, Doglioni C, Dagna L.
Abstract
Objective
Microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) are systemic, necrotizing, small-vessel vasculitis associated with circulating anti-neutrophil cytoplasmic autoantibodies (ANCA), and thus called ANCA-associated vasculitides (AAV). Aim of the present study is to evaluate a potential role of interleukin (IL)-6 and its pathway in the pathogenesis of AAV and to review previous evidences of IL-6 in MPA and GPA.
Methods
Blood and histological samples, from 10 untreated myeloperoxidase (MPO)-ANCA/proteinase 3 (PR3)-ANCA positive patients with active AAV were studied. Serum levels of cytokines/chemokines were evaluated by means of a Bio-Plex Multiple Cytokine Assay. IL-6 production at sites of active vasculitis was assessed by means of both immunohistochemistry and in situ hybridization techniques. We also treated a patient with MPA who was resistant or allergic to conventional treatments with a 12-month course of the IL-6 inhibitor tocilizumab, and followed him up for 24 additional months. We also reviewed all the published cases in the English literature of histologically-confirmed MPA or GPA, in which elevated IL-6 serum levels or intralesional IL-6 expression were reported.
Results
IL-6 serum levels were significantly increased in patients with AAV as compared to controls (median, 51.96 pg/mL; range, 34.11 - 84.30; versus 0.68 pg/mL; range, 0.01 – 1.81; P <0.005). Also, IL-6 was expressed and produced at sites of active vasculitis. Treatment with tocilizumab was able to induce a complete and sustained disease remission in a patient with severe multisystemic MPA, as well as normalization of circulating levels of IL-6-associated pro-inflammatory cytokines and chemokines. Previous evidences of IL-6 pathway activation in AAV are scarce. Seven clinical studies for a total of approximately 120 patients, mainly affected by GPA, reported increased serum levels of IL-6.
Conclusion
The finding of an activated IL-6 pathway in patients with AAV, together with the observed effects of tocilizumab monotherapy, provides evidence for a possible central role of IL-6 in the pathogenesis of AAV and suggests its targeting as a potential treatment.
