Despite the prevalence and clinical importance of influenza, its long-term effect on lung immunity is unclear. Here we describe that following viral clearance and clinical recovery, at 1 month after ...infection with influenza, mice are better protected from Streptococcus pneumoniae infection due to a population of monocyte-derived alveolar macrophages (AMs) that produce increased interleukin-6. Influenza-induced monocyte-derived AMs have a surface phenotype similar to resident AMs but display a unique functional, transcriptional and epigenetic profile that is distinct from resident AMs. In contrast, influenza-experienced resident AMs remain largely similar to naive AMs. Thus, influenza changes the composition of the AM population to provide prolonged antibacterial protection. Monocyte-derived AMs persist over time but lose their protective profile. Our results help to understand how transient respiratory infections, a common occurrence in human life, can constantly alter lung immunity by contributing monocyte-derived, recruited cells to the AM population.
Influenza A virus (IAV)‐induced severe disease is characterized by infected lung epithelia, robust inflammatory responses and acute lung injury. Since type I interferon (IFNαβ) and type III ...interferon (IFNλ) are potent antiviral cytokines with immunomodulatory potential, we assessed their efficacy as IAV treatments. IFNλ treatment of IAV‐infected Mx1‐positive mice lowered viral load and protected from disease. IFNα treatment also restricted IAV replication but exacerbated disease. IFNα treatment increased pulmonary proinflammatory cytokine secretion, innate cell recruitment and epithelial cell death, unlike IFNλ‐treatment. IFNλ lacked the direct stimulatory activity of IFNα on immune cells. In epithelia, both IFNs induced antiviral genes but no inflammatory cytokines. Similarly, human airway epithelia responded to both IFNα and IFNλ by induction of antiviral genes but not of cytokines, while hPBMCs responded only to IFNα. The restriction of both IFNλ responsiveness and productive IAV replication to pulmonary epithelia allows IFNλ to limit IAV spread through antiviral gene induction in relevant cells without overstimulating the immune system and driving immunopathology. We propose IFNλ as a non‐inflammatory and hence superior treatment option for human IAV infection.
Synopsis
IFNα and IFNλ are both antiviral cytokines. IFNλ appears to confer better protection than IFNα in influenza experimentally infected organisms, as it helps control the virus in infected target cells in airway epithelia, and does not enhance inflammation in the lung.
Both interferon alpha (IFNα) and lambda (IFNλ) protect from influenza virus infection when mice are treated prior to infection.
When infected mice are treated therapeutically after onset of symptoms, IFNλ protects but IFNα aggravates disease.
Both IFNα and IFNλ have antiviral effects, but IFNα also activates immune cells in the lung leading to immunopathology, while IFNλ does not.
The response pattern to IFNα and IFNλ of human immune cells and lung epithelia is identical to that of mouse cells, strongly suggesting that the same effects would be found in humans.
IFNα and IFNλ are both antiviral cytokines. IFNλ appears to confer better protection than IFNα in influenza experimentally infected organisms, as it helps control the virus in infected target cells in airway epithelia, and does not enhance inflammation in the lung.
Prophylactic strategies are urgently needed for prevention of severe inflammatory responses to respiratory viral infections. Bacterial-host interactions may modify the immune response to viral ...infections.
We examined the contribution of Intranasal administration of two different Bifidobacterium longum strains or its isolated cell wall in controlling viral induced inflammation using a murine model of influenza infection. We monitored mortality and morbidity over a 10-day period and viral load, differential broncho alveolar lavage (BAL) fluid inflammatory cell counts, Lung tissue histology, BAL and serum cytokines, markers of vascular damage and cell death were quantified.
Intranasal administration of Bifidobacterium longum35624® or its isolated cell wall prior to virus inoculation significantly reduced viral load within the lungs and significantly improved survival. Reduced viral load was associated with reduced lung injury as suggested by cell death and vascular leakage markers, a shift from neutrophil to macrophage recruitment, reduced inflammatory cytokine levels (including IL-6), reduced type 1 and 2 interferon levels, but increased levels of interferon-λ and surfactant protein D. These protective effects were maintained when the bifidobacterial cell wall preparation was administered 24 h after viral inoculation. The protective effects were also observed for the Bifidobacterium longumPB-VIR™ strain.
Exposure to these bifidobacterial strains protect against the inflammatory sequelae and damage associated with uncontrolled viral replication within the lung.
This work has been funded, in part, by a research grant from GlaxoSmithKline, PrecisionBiotics Group Ltd., Swiss National Science Foundation grants (project numbers CRSII3_154488, 310030_144219, 310030_127356 and 310030_144219) and Christine Kühne – Center for Allergy Research and Education (CK-CARE).
Interaction of pathogens with cells of the immune system results in activation of inflammatory gene expression. This response, although vital for immune defence, is frequently deleterious to the host ...due to the exaggerated production of inflammatory proteins. The scope of inflammatory responses reflects the activation state of signalling proteins upstream of inflammatory genes as well as signal-induced assembly of nuclear chromatin complexes that support mRNA expression. Recognition of post-translationally modified histones by nuclear proteins that initiate mRNA transcription and support mRNA elongation is a critical step in the regulation of gene expression. Here we present a novel pharmacological approach that targets inflammatory gene expression by interfering with the recognition of acetylated histones by the bromodomain and extra terminal domain (BET) family of proteins. We describe a synthetic compound (I-BET) that by 'mimicking' acetylated histones disrupts chromatin complexes responsible for the expression of key inflammatory genes in activated macrophages, and confers protection against lipopolysaccharide-induced endotoxic shock and bacteria-induced sepsis. Our findings suggest that synthetic compounds specifically targeting proteins that recognize post-translationally modified histones can serve as a new generation of immunomodulatory drugs.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The PI3K signaling pathway regulates cell growth and movement and is heavily mutated in cancer. Class I PI3Ks synthesize the lipid messenger PI(3,4,5)P
. PI(3,4,5)P
can be dephosphorylated by 3- or ...5-phosphatases, the latter producing PI(3,4)P
. The PTEN tumor suppressor is thought to function primarily as a PI(3,4,5)P
3-phosphatase, limiting activation of this pathway. Here we show that PTEN also functions as a PI(3,4)P
3-phosphatase, both in vitro and in vivo. PTEN is a major PI(3,4)P
phosphatase in Mcf10a cytosol, and loss of PTEN and INPP4B, a known PI(3,4)P
4-phosphatase, leads to synergistic accumulation of PI(3,4)P
, which correlated with increased invadopodia in epidermal growth factor (EGF)-stimulated cells. PTEN deletion increased PI(3,4)P
levels in a mouse model of prostate cancer, and it inversely correlated with PI(3,4)P
levels across several EGF-stimulated prostate and breast cancer lines. These results point to a role for PI(3,4)P
in the phenotype caused by loss-of-function mutations or deletions in PTEN.
The PI3K signaling pathway regulates cell growth and movement and is heavily mutated in cancer. Class I PI3Ks synthesize the lipid messenger PI(3,4,5)P3. PI(3,4,5)P3 can be dephosphorylated by 3- or ...5-phosphatases, the latter producing PI(3,4)P2. The PTEN tumor suppressor is thought to function primarily as a PI(3,4,5)P3 3-phosphatase, limiting activation of this pathway. Here we show that PTEN also functions as a PI(3,4)P2 3-phosphatase, both in vitro and in vivo. PTEN is a major PI(3,4)P2 phosphatase in Mcf10a cytosol, and loss of PTEN and INPP4B, a known PI(3,4)P2 4-phosphatase, leads to synergistic accumulation of PI(3,4)P2, which correlated with increased invadopodia in epidermal growth factor (EGF)-stimulated cells. PTEN deletion increased PI(3,4)P2 levels in a mouse model of prostate cancer, and it inversely correlated with PI(3,4)P2 levels across several EGF-stimulated prostate and breast cancer lines. These results point to a role for PI(3,4)P2 in the phenotype caused by loss-of-function mutations or deletions in PTEN.
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•PTEN is a PI(3,4)P2 3-phosphatase•PTEN and INPP4B regulate PI(3,4)P2 accumulation downstream of class I PI3K•PTEN regulates PI(3,4)P2-dependent activation of Akt and formation of invadopodia•PI(3,4)P2 signaling may play a role in the tumor suppressor function of PTEN
Malek et al. show that the tumor suppressor PTEN acts as a PI(3,4)P2 3-phosphatase within the growth factor-stimulated PI3K signaling network, in addition to its accepted role as a PI(3,4,5)P3 3-phosphatase. This suggests that specific PI(3,4)P2 effector functions, such as invadopodia formation, play a role in the PTEN-loss-of-function phenotype.
Recurrent chromosomal translocations involving the mixed lineage leukaemia (MLL) gene initiate aggressive forms of leukaemia, which are often refractory to conventional therapies. Many MLL-fusion ...partners are members of the super elongation complex (SEC), a critical regulator of transcriptional elongation, suggesting that aberrant control of this process has an important role in leukaemia induction. Here we use a global proteomic strategy to demonstrate that MLL fusions, as part of SEC and the polymerase-associated factor complex (PAFc), are associated with the BET family of acetyl-lysine recognizing, chromatin 'adaptor' proteins. These data provided the basis for therapeutic intervention in MLL-fusion leukaemia, via the displacement of the BET family of proteins from chromatin. We show that a novel small molecule inhibitor of the BET family, GSK1210151A (I-BET151), has profound efficacy against human and murine MLL-fusion leukaemic cell lines, through the induction of early cell cycle arrest and apoptosis. I-BET151 treatment in two human leukaemia cell lines with different MLL fusions alters the expression of a common set of genes whose function may account for these phenotypic changes. The mode of action of I-BET151 is, at least in part, due to the inhibition of transcription at key genes (BCL2, C-MYC and CDK6) through the displacement of BRD3/4, PAFc and SEC components from chromatin. In vivo studies indicate that I-BET151 has significant therapeutic value, providing survival benefit in two distinct mouse models of murine MLL-AF9 and human MLL-AF4 leukaemia. Finally, the efficacy of I-BET151 against human leukaemia stem cells is demonstrated, providing further evidence of its potent therapeutic potential. These findings establish the displacement of BET proteins from chromatin as a promising epigenetic therapy for these aggressive leukaemias.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Recent studies using super-resolution microscopy have established that the organisation of immune cell receptors impacts signal integration and cellular activation. Understanding the ...nano-scale dynamics of surface receptors on tissue specific macrophages is especially important, as they are phenotypically diverse and possess a large repertoire of receptors. However, tissue macrophages are highly auto-fluorescent, severely limiting the utility of light microscopy. Here, we report a novel correction technique which utilises a moving median filter to remove auto-fluorescent noise from stochastic optical reconstruction microscopy datasets. Using this, we visualised lung macrophages (LMs) activated through Fc receptors by IgG-coated glass slides, representing a 2D model of the phagocytic synapse. This unexpectedly revealed the formation of protrusions, at the surface of LMs but not blood-derived macrophages. Class I MHC protein accumulated at the tips, consistent with a role for macrophage protrusions in antigen presentation. Additionally, staining for the exosome marker CD81 revealed the secretion of extracellular vesicles. Classically, cell-derived vesicles are studied after bulk isolation, which is harsh and comes with many caveats. Imaging them directly upon secretion allows analysis of their properties on a cell-by-cell basis in a near-native state. We discovered that LM vesicles appeared distinct from those secreted from blood-derived macrophages in that their average diameter was much smaller (80 nm ± 19 nm vs. 159 nm ± 78 nm). Thus, our correction method for super-resolution microscopy revealed novel cell biology – protrusion formation and vesicle secretion – triggered upon activation of human LMs.
Stimulation of cells with tumor necrosis factor α (TNFα) triggers NF-κB1 p105 proteolysis, releasing associated Rel subunits to translocate into the nucleus and modulate target gene expression. ...Phosphorylation of serine 927 within the p105 PEST region by the IκB kinase (IKK) complex is required to promote p105 proteolysis in response to TNFα stimulation. In this study, the role of the p105 death domain (DD) in signal-induced p105 proteolysis is investigated. Endogenous p105 is shown to interact with the IKK complex in HeLa cells, and transient transfection experiments in 293 cells indicate that each of the catalytic components of the IKK complex, IKK1 and IKK2, can bind to p105. Interaction of p105 with both IKK1 and IKK2 is substantially reduced by deletion of the p105 DD or introduction of a specific point mutation (L841A) into the p105 DD homologous to thelpr mutation in Fas. Phosphorylation of immunoprecipitated p105 on serine 927 by purified recombinant IKK1 or IKK2 proteinin vitro is dramatically reduced in both DD mutants relative to wild type. Furthermore, both of the DD mutations significantly impair the ability of low concentrations of IKK2 to induce p105 serine 927 phosphorylation and proteolysis in transiently transfected 3T3 cells. However, high levels of transiently expressed IKK2 bypass the requirement for the p105 DD to induce p105 serine 927 phosphorylation. Finally, p105 serine 927 phosphorylation by the endogenous IKK complex after TNFα stimulation and subsequent p105 proteolysis is blocked in both p105 DD mutants when stably expressed in HeLa cells. Thus, the p105 DD acts as a docking site for IKK, increasing its local concentration in the vicinity of the p105 PEST region and facilitating efficient serine 927 phosphorylation.
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